“szskw”通过精心收集，向本站投稿了6篇Planting trees习题2，这里小编给大家分享一些Planting trees习题2，方便大家学习。
篇1：Planting trees习题2
Planting trees习题精选2
习题精选I. 找出与所给单词划线部分读音相同的词。
1. stick A. machine B. mountain C. straight D. leave
2. water A. watch B. cover C. northern D. farmland
3. fruit A. build B. student C. good D. move
4. deep A. metre B. forest C. difficult D. great
5. among A. south B. southern C. along D. plant
Ⅱ．词汇
A) 根据各句子的内容，完成句中已给了首字母的单词。
1. If you're late again, your teacher will be a ________ with you.
2. Thirty-six and sixty-four is h ________.
3. Everything is getting on well! We can't find anything u ________
4. ―Which is your f________ food? ―Fish. I like it best.
5. Saturdays and Sundays are h________, so we don't work.
B）词形转换：用所给词的.相关形式填空。
6. We should plant trees on Tree ______ Day. (plant)
7. In the world about three _____ of books are written in English. (four)
8. Each book has two _____ : the front and the back. (cover)
9. More food is ______ (need) at that time.
10. The hole must be dug 4 metres ______. (deeply)
C)词语释义：根据释义及词首字母写出相应的单词。
11. m______ one thousand.
12. c______ try to do the same as the others
13. o_____ more than
14. a______ in the middle of
15. a_____ nearly
III．选择填空。
1. I think that it’s the ______ book I’ve read.
A. more interesting B. very interesting C. interested D. most interesting
2. Nobody can stop me from ______ the work.
A. do B. doing C. did D. done
3. These dirty clothes ______ in half an hour.
A. must be washed B. must wash C. must be wash D. will wash
4. Neither she nor I ______ going to the cinema this evening.
A. am B. is C. are D. were
5. I tied the tree to the top of the stick ______ it was straight.
A. in order to B. for C. so that D. but
6. ______ you ______ I am a worker.
A. Both, and B. Either, and C. No, but D. Neither, nor
7. There are many ______ stars in the sky at night.
A. thousands of B. thousand of C. thousand D. thousands
8. I hope _______ the film soon.
A. will see B. to see C. seeing D. see
9. Did a hole ________ for the tree.
A. large enough B. enough large C. largely D. enough
10. Spring is the best time ______ trees.
A. planting B. for planting C. for plant D. plant
11. He likes not only skating in winter but also _____in summer.
A. to swimming B. swimming C. swims D. to swim
12. He is leaving for Shanghai ______ time to have a meeting
A. in three day's B. after three day's
C. after three days D. in three days'
13. That small town is 1000 kilometres ___
A. far B. farther C. away D. farthest
14. All babies should ______.
A. be looking after B. be look after
C. look after D. be looked after
15. Must this article be typed at once? No, it ___
A. mustn’t B. needn’t C. can't D. may not
16. In 1850, about a third of the USA ______ by forests.
A. were cover B. was covered C. has been covered D. were covered
17. _________you sleep, ______ you'll be.
A. Much, lazy B. More, lazier C. The more, the lazier D. The more, the lazy
18. Make sure ______ the young tree must be straight.
A. that B. how C. what D. which
19. Why are you ______ old clothes today?
A. into B. in C. wear D. dress
20. Bruce and Bill ______ many Chinese books in the past few years.
A. read B. are reading C. were reading D. have read
21. _______ of the two boys likes English.
A. Both B. Neither C. Some D. Everyone
22. Don’t jump. The river is about four metres_______.
A. long B. wide C. thin D. high
23. A lot of good land has gone with them, ______ only sand.
A. leaving B. to leave C. left D. leaves
24. Babies should _____ well.
A. take good care of B. looked after C. be takes care D. be looked after
25. He wanted to know what ______ her.
A. happened on B. had happened to C. was happening at D. had happened with
B) 情景交际
26. M: ______?
W: Thank you. That’s very nice of you.
A. May I help you. B. How are you.
C. Would you like to take my seat
27. M: Do you need my help? W: _____.
A. I like to do it by yourself B. It’s difficult C. No, thanks
28. W: Excuse me, would you please help me fill the bag with some paper?
M: _______.
A. No, I have no time. B. With please, thanks
C. Of course, glad to help
29. W: Do you think his radio is too noisy?
M: _____. Please ask him to turn it down.
A. I don’t think so B. I think so C. I don’t mind
30. W: What are you looking for?
M: My lost bike. _____?
A. Have you found it before B. Did you see it
C. Have you seen it anywhere
IV．补全对话
A）根据对话内容写出下列所缺单词（首字母已给出）。
A: Do you know how to p__1__ a tree?
B: Yes, more or l__2__. First it’s best to plant trees in s___3___. And the ground must be n___4__ too wet nor too dry.
A: What must be d___5___ to plant a tree?
B: Well. A hole must be dug large e__6___ for the tree. But the hole should not be too d___7___.
A: Shall we k___8___ a long stick into the earth next to the hole?
B: Yes. You’d better do that to make sure that it is s___9___.
A: Can the tree be watered as soon as the earth is put back?
B: Of course. The tree must be watered well as often as p___10___.
B）从七个句子中，选择五个句子完成对话。
―Where shall we go today?
―Shall we go to the Great Wall?
― 11 What about going to the Temple of Heaven?
― 12 What do you know about it?
―It's one of the biggest and famous parks in Beijing. It was a place where kings worship the God(祭天).
― 13 .
―It's in the middle of the southern pant of the city.
― 14 .
―It's about 18 kilometres from the Friendship Hotel.
―____15____.
―I’d prefer to go by bike.
―OK. Let's get ready.
A. That's a good idea.
B. Well, I think we should do that tomorrow.
C. Shall we go by bus or by bike?
D. Is it near from the Friendship Hotel?
E. How far is it?
F. How long is it?
G. Where is it?
V．句型转换。
1. You must tie the tree to top of the stick. （改为被动语态）
The tree must _______ ________ to the top of the stick.
2. Jim hasn’t seen the film and his friends haven’t, either.（合成一句）
Neither Jim’s friends ______ he _____ seen the film.
3. She got up very early so that she could catch the first bus.（变同义句）
She got up very early _______ ________ the first bus.
4. Can my bike be mended, Uncle Wang?（变主动语态）
_____ you ______ my bike, Uncle Wang?
5. He didn’t leave anything and went out.
He went out ______ ______ anything.
6. We should speak to the old man like that.（改为含被动语态的否定句）
The old man ______ be ______ ______ like that.
7. Lucy sings well, and Lily sings well, too.
______ Lucy ______ Lily ______ well.
8. The meeting-room is quite large. It can hold 200 people.
The meeting-room is ______ ______ ______ hold 200 people.
9. The hole is large enough to hold the tree.
The hole is ______ large ______ it can hold the tree.
10. The trees grow well because of the rain.
______ ______ the rain, the trees grow well.
VI. 根据汉语意思完成句子。
1. 明天上学穿新衣服。
Come to school ______ ______ ______ ______ tomorrow.
2. 还有三十多棵树要植呢。
There are thirty ______ ______ to ______ ______.
3. 他得到的越多，想要的越多。
______ ______ he gets ______ ______ he wants.
4. 果实必须在秋季摘。
______ must ______ ______ in autumn.
5. 你的作业做完了吗？差不多了。
Have you finished your homework? ______ ______ ______.
6. 我们俩都累了，但没有一个停下来休息。
______ of us are tired, but ______ ______ us stops to have a rest.
7. 这座山被森林覆盖着。
The mountain ______ ______ ______ forests.
8. 这条河有1500多公里长。
This rive is over 1500 ______ ______.
Ⅶ. 完形填空。
Tree Planting Day was started in the year 1979. Every year___1___ March 12th, office workers, soldiers, workers, school children and old people go out to plant trees.
Last week, Class 3 went to plant some trees on Tree Planting Day. Everybody___2___old clothes. They met in the school ___3__, and then walked to a park about four kilometers away from the school. They sang songs ___4___ they were walking. Miss Zhang and several other teachers went with them.
When they arrived at the park, they started to work. A truck___5__ many young trees to the park. The children took them from the truck, and carried them to the right place. They worked together____6___. They ___7___to dig holes in the ground. It was hard work, but they really enjoyed it. When the holes were___8___, they put the young trees in the holes, and then filled them again. They __9___ the earth hard with their feet. Then they got water from a river, and watered the trees well. They also watered some of the older trees, too.
___10___ they were very happy. That day they planted over 2, 500 trees.
“Well done!” said Miss Zhang. “You’re done very well today!”
1. A. at B. on C. in D. of
2. A. was wearing B. was putting up C. has worn D. put on
3. A. never B. always C. as often D. as usual
4. A. while B. before C. after D. as soon as
5. A. took B. had C. brought D. bough
6. A. of pairs B. in pairs C. on pair D. at pairs
7. A. took to turn B. took turns C. have taken turns D. take turns
8. A. high enough B. enough deep C. long enough D. deep enough
9. A. pull out B. pushed up C. pushed down D. deep enough
10. A. At the beginning of the day B. By the end of the day
C. In the end of the day D. At the end of the day
Ⅷ．阅读理解
（1）
A strange thing happened to Henry yesterday. He was on a bus and wanted to get off. So he stood up and rang the bell. To make sure the driver heard him he rang it twice, but the bus didn't stop, and the conductor came and shouted at him. The conductor was so angry and spoke so fast that Henry didn’t understand a word. The bus stopped at the next bus stop and Henry got off. As he got off he heard someone say, “I think he is a foreigner, for he doesn't know the rule here.” When Henry got home, he told his wife about his story on the bus. “How many times did you ring the bell?” she asked. “Twice,” said Henry. “Well, that tells the driver to go on.” his wife said. “Only the conductor can ring the bell twice.” Henry nodded. “I see.” he said.
1. Usually when people wanted to stop at the bus stop in the town, they ______.
A. shouted at the bus conductor B. rang the bell once
C. rang the bell twice D. asked the conductor to keep the bell ringing
2. Henry rang the bell twice in order to ______.
A. make the conductor angry B. make people on the bus laugh
C. let the driver stop the bus D. let people know that he was a foreigner
3. ______ knew the rule of ringing on a bus.
A. Most of the local (当地的)people in the town
B. All the people in the town
C. Nobody in the town D. No one but Henry's wife
4. Did Henry often take a bus in the town?
A. Yes, he did. B. No, never.
C. Yes, very often. D. No, not very often.
5. Henry realized (认识到) his mistake ______ .
A. when he got off the bus B. when he was on the bus
C. after he got home D. after his wife said it to him
（2）
Once Effendi（阿凡提） had a joke with the Prime Minister(宰相). He said that the Minister would die the next day. Really the next day, the Minister fell off the horse and died. When the King learned this, he got angry and sent his men to catch Effendi at once.
When Effendi was brought to him, the King shouted angrily, “Effendi, since you know when my Minister would die, you must know the date of your own death. Say it out, or you will die today.”
Effendi looked at the King for a while, he answered, “But how can I know? I'll die two days earlier than you.”
Because the king was afraid if he killed Effendi, he himself would die after that. He thought he must keep Effendi alive(活着) as long as possible, so he let Effendi go.
6. This story tells us ______.
A. how Effendi fooled (愚弄) the king B. When the king would die
C. Why the Minister died D. Effendi knew the dates of everyone's death
7. The Prime Minister died because ______.
A. Effendi killed him B. Effendi said he would die
C. he was badly ill D. he fell to the ground from the horse
8. Why did the king ask Effendi to tell him the date of his own death?
Because ______.
A. (in this way) the King would know when he would die
B. he wanted to find an excuse to kill Effendi
C. he himself had known the date of Effendi's death
D. he wanted to know when Effendi would die
9. The King let Effendi go because ______.
A. he hoped to live a long life B. he was afraid of Effendi
C. he didn't believe (相信) Effendi's words
D. he knew he would die two days later
10. Which of the following is not true?
A. The Minister died after the day when Effendi played a joke on him
B. The King was afraid of death
C. Effendi didn't know when the King would die
D. If the King killed Effendi, he himself would die two days later
（3）
From a plane we can see the fields, cities, mountains or seas below. If we go into space, we see more and more of the earth. People and man―made satellites(人造卫星) have been sent up into space(太空)to look at the earth carefully and people have learnt more about the earth in the last few years.
The sea looks very beautiful when the sun is shining on it. But it can be very terrible(可怕的) when there is a strong wind.
The sea is very big. It nearly covers three quarters of the earth. The sea is also very deep in some places. There is one place and at that place the sea is about 11 kilometres deep. The highest mountain in the world is about 9 kilometres high. If that mountain was put into the sea at that place, there would be still 2 kilometres of water above it!
In most parts of the sea, there are many kinds of fishes and plants (植物). Some live near the top of the sea. Others live deep down. There are also a lot of small living things, and lots of fishes live by eating them.
The sea can be very cold. When people go down, the sea becomes colder and colder. Only some men can go down into the deep sea. But in 1970, five women scientists(科学家) lived in the deep sea for 14 days.
11. This passage is ______.
A. a short story B. for science reading C. a piece of news D. a report
12. The sea covers about ______ of the world.
A. 1/3 B. 1/4 C. 2/4 D. 3/4
13. ______ are not mentioned (提及) in this passage.
A. Fishes B. Plants C. Islands D. Living things
14. Which of the following is NOT true?
A. The sea is usually beautiful when the sun is shining
B. The sea is always very terrible when the wind blows hard
C. The highest mountain is in the deepest place of the sea
D. The deeper the people go into the sea, the colder they will feel
15. The last sentence “'But in 1970, five women scientist lived in the deep sea for fourteen days” means that ______.
A. Women wanted to live in the deep sea for a long time
B. Women could go deeper into the sea than men
C. Women liked living in the deep sea better than men
D. Women could do the same work as men.
答案：Ⅰ.1. B 2.C 3.D 4.A 5.B
Ⅱ. 1. angry 2. hundred 3.unusual 4. favourite 5. holidays 6. Planting 7. quarters 8. covers 9. needed 10. deep 11. million 12. copy 13. over 14. among 15. almost
Ⅲ. 1.D 2.B 3.A 4.A 5.C 6.D 7.A 8.B 9.A 10.B 11.B 12.D 13.C 14.D 15.B 16.B 17.C 18.A 19.B 20.D 21.B 22.B 23.A 24.D 25.B 26. C 27.C 28.C 29.B 30.C
Ⅳ. 1.plant 2.less 3.spring 4.neither 5.done 6.enough 7.deep 8.knock 9.straight 10.possible 11-15 B A G E C
Ⅴ. 1. be tied 2. nor, has 3. to catch 4. Can, mend 5. without leaving 6. shouldn’t, spoken to 7. Both, and, sing 8. large enough to 9. so, that 10. Thanks to
Ⅵ. 1. in your new clothes 2. more trees, be planted 3. The more, the more 4. Fruit, be harvested 5. More or less 6. Both, neither of 7. is covered with 8. kilometers long
Ⅶ. 1-5 B A D A C 6-10 B B D C D
Ⅷ.1-5 B C A D D 6.A 7.D 8.B 9.A 10.D 11.B 12.D 13.C 14.C 15.D
篇2：《诗词曲》习题2
一、语言的积累与运用
1、选出下面注音完全正确的一项
A、烂柯（kē） 酬乐天（chóu） 折戟（jī）
B、干戈（gē） 认前朝（cháo） 宫阙（què）
C、琼楼（qióng） 贬谪（zhāi） 零丁（dīng）
D、婵娟（chán） 踌蹰（chǔ） 绮户（qǐ）
2、选出下面书写完全正确的一项是（）
A、巴山楚水萋凉地，二十三年弃置身。
B、折戟沉沙铁未消，自将磨洗认前朝。
C、山河破碎风飘絮，身世浮沉雨打平。
D、人有悲欢离合，月有阴晴圆缺。
3、选出下面朗读节奏不正确的一项是（）
A、沉舟｜侧畔｜千帆｜过，病树｜前头｜万木｜春。
B、折戟｜沉沙｜铁未销，自将｜磨洗｜认前｜朝。
C、辛苦｜遭逢｜起一｜经，干戈｜寥落｜四周｜星。
D、我欲｜乘风归去，又恐｜琼楼玉宇。
4、选出对加粗词解释不正确的一项是（）
A、酬乐天（以诗答谢） 长精神（振作） 自将磨洗（将要）
B、折戟（古代兵器） 铁未销（销蚀） 叹零丁（孤苦无依）
C、丹心（比喻忠心）不胜寒（承受、经受） 干戈寥落（指代战争）
D、经行处（经过） 共婵娟（指月亮） 照汗青（指史册）
5、默写或理解性填空。
⑴_____________，暂凭杯酒长精神。
⑵《酬乐天扬州逢席上见赠》的名句是_____________。
⑶《过零丁洋》中比喻飘摇不定的南宋朝廷的一句是_____________。
⑷《水调歌头》中写出词人矛盾心理的`一句是_____________。
⑸《山坡羊?潼关怀古》写曲人驻马远望、感慨横生的诗句是_____________。
6、说出你对下面名句的理解。
⑴东风不与周郎便，铜雀春深锁二乔。
________________________________________________________
⑵但愿人长久，千里共婵娟。
_______________________________________________________
二、阅读下面短文，回答问题
明月几时有？把酒问青天。不知天上宫阙，今夕是何年。我欲乘风归去，又恐琼楼玉宇，高处不胜寒。起舞弄清影，何似在人间。转朱阁，低绮户，照无眠。不应有恨，何事长向别时圆？人有悲欢离合，月有阴晴圆缺，此事古难全。但愿人长久，千里共婵娟。
1、给下列几句划分节奏。
明月几时有？把酒问青天。不知天上宫阙，今夕是何年。我欲乘风归去，又恐琼楼玉宇，高处不胜寒。
2、“起舞弄清影”中的“弄”字用得极妙，妙在何处？
_________________________________________________________
3、谢庄的《月赋》中有“隔千里兮共明月”的诗句，与本词中的最后一句意思相近，但在意境上不尽相同，试分析。
_________________________________________________________
三、能力题
选出对张养浩《山坡羊?潼关怀古》理解分析不正确的一项是（）
峰峦如聚，波涛如怒，山河表里潼关路。望西都，意踌蹰。伤心秦汉经行处，宫阙万间都做了土。兴，百姓苦；亡，百姓苦！
A、《山坡羊?潼关怀古》是一首元代散曲，“山坡羊”是曲牌名，“潼关怀古”是曲的标题。
B、“山河表里潼关路”这句勾画出潼关外有黄河，内有华山，山河雄伟，地势险要的特点。
C、曲中的“聚”字赋予静止的峰峦以动感，“怒”字则生动地表现出波涛汹涌澎湃的情态。
D、作者在曲中表达出深深的伤感悲愤之情，他伤感悲愤的最主要原因是“宫阙万间都做了土”。
四、语言的创新与应用。
1、请写出你知道的古今中外的名人关于学习方面的名言两句。
⑴______________________________________________________
⑵______________________________________________________
2、默写。
⑴_____________，水涨起来了，太阳的脸红起来了。
⑵古代诗歌中抒写思念故乡、眷恋亲友的诗句很多，请你写出三句（其中一句是课外的）。 ①_____________，_____________。
②_____________，_____________。
③_____________，_____________。
3、举出中国历史上有哪些“留取丹心照汗青”的英雄人物？不少于三例
_________________________________________________________
篇3：《Water sports 》同步习题2
《Water sports 》同步习题（2）
根据句意选择合适的词语填空。1). The important thing is to be good at ______.
We must ______ this problem carefully, (study, learn)
2). When you _______a street, you must walk _______it quickly and not run. (cross, across)
3). During this holiday, I'm going to make a long _______ with my family. (journey, trip)
4). My son is my ________. He can speak English very well.
I'm ______of knowing the football star. (pride, proud)
5). The children have ______made a snowman. They are singing and dancing around it.
The children made a snowman ______. (just, just now)
6). ______ Tom ______ I are happy to be your students.
______ Tom ______ I am good at painting. (both…and…, neither…nor…)
答案
1)．learning 此句意思是：重要的'事情是要学会学习。）study（我们必须认真研究这个问题。研究用study。）
2)．Cross, across（第一个空需要一个动词，而第二个空由于前面有动词walk所以需要一个介词。）
3)．journey（长途旅行用journey）
4)．pride（意思是我的儿子是我的骄傲。用名词。）proud（我以认识那位球星为荣。用be proud of句型。）
5)．just（第一句是现在完成时的句子，所以用just表示刚堆完雪人，不强调具体什么时间堆，而主要强调雪人堆完后现在孩子们的心情。）just now（第二句动词用过去时，强调过去的具体某个时间做的这件事。译文是：孩子们刚才堆的雪人。）
6)．both…and…（此句关键词是are和students。Both…and…做主语时谓语动词用复数形式。）neither…nor…（此句关键词是am。因为这个词组做生语时谓语动词根据紧挨着的人称而定。所以nor后面的主语是I因此动词用am。）
篇4：Unit 4 Travel习题2
Unit 4 Travel习题精选（2）
习题精选
I．词汇
A）根据首字母和英文释义，完整单词。
1. The word o___________ shows that something belongs to a person or another thing
2. The word p___________ means to do something so often that one will be good at it.
3. Do you m______ if I sit here?
4. The music is bright and l______.
5. They had an e______ time in Sydney.
答案：1. own 2. practise 3. mind 4. lively 5. enjoyable
B) 用所给词的适当形式填空。
1. Which is ____, traveling by air, by train or by ship? ( popular)
2. As soon as he went to bed, he fell ____. (sleep)
3. Jim thinks travelling by train is far more _______ than by air. (enjoy)
4. What do you think is the ______ way to travel ? (comfortable)
5. You must return the library books ______. (you)
答案：1.the most popular 2. asleep 3. enjoyable 4. most comfortable 5. yourself
C) 选用下列动词适当的形式填空，并作相应的'变化
take get pass offer go fall
travel show leave speak hurry sell
1. Mother tried to practise ________ English every day.
2. He ________ asleep soon after he went to bed.
3. ________ forever are the days when you look young!
4. Don't ________ it on to the next student!
5. They keep ________ us some tea at the meeting.
6. Would you like to ________ me around your factory?
7. ________ up, or you’ll be the last one to ________ to the top of the hill.
8. She ________ a kind of new apples in her shop now.
答案：1. speaking 2. fell 3. Gone 4. pass 5. offering 6. show 7. Hurry, get 8. is selling
II．完成句子
A) 句型转换
1. Wei Hua was washing clothes last night. (对画线部分提问)
________ ________Wei Hua ________clothes?
2. You’d better get to sleep earlier, or you’ll be tired. (同义句转换)
If you ________ ________ ________earlier, you won't be tired.
3. While we were talking, the teacher came in. (对画线部分提问)
________did the teacher________ ________?
4. He saw the bag before his bike hit it. (用until转换)
He________ ________the bag ________his bike hit it.
5. You help me with English. It's nice of you. (连成一句)
It’s nice of you ________ ________ ________with English.
答案： 1. when, was, washing 2. get, to, sleep 3. when, come, in 4. didn’t, see, until 5. to, help, me
B）不改变原意，改写句子：
1. I’m sorry he isn’t here right now.
I'm sorry he’s ________the____.
2. I hope to see him as soon as possible.
I hope to see him as ____as ____ ____.
3. He says that he won't be free until tomorrow.
He says that he____ ____free ____tomorrow.
4. Jim Green has been in China for more than two years.
Jim Green ____to China ____two years ____.
5. It's best to travel by train.
____by train ____the ____.
6. They went to Chengdu by train.
They ____a____ ____to Chengdu.
7. Everybody is here except Jim Green.
____Jim Green ____here.
8. It’ll take us two weeks to spend our holiday in the country.
We’ll have our ____ ____in the country.
答案：
1. out, at, moment 2. soon, I, can 3. will, be, after
4. came, over, ago 5. Travelling, is, best 6. took (had), train, ride
7. Only, isn’t 8. two-week, holiday
C）从方框内中，选择合适的句子完成对话。
Bob: Hello, Cathy!
Cathy: Hello, Bob! 1 .
Bob: What does Alice say?
Cathy: Alice says that 2 . They want you to go with them.
Bob: When and where will they meet?
Cathy: Alice says that 3 .
Bob: How can they go there?
Cathy: Alice says that 4 .
Bob: What else does she say?
Cathy: Oh, she says that 5 .
Bob: OK. Thank you.
Cathy: Not at all.
A. you will bring some food with you and not to be late
B. they will meet at the school gate at half past seven
C. Alice has just called you
D. they will go there by bus
E. Lin Tao, Kate and Alice are going to have a picnic at the West Hill this Sunday
答案：CEBDA
篇5：电路原理课后习题答案2
电路原理课后习题答案2
第五版《电路原理》课后作业 第一章“电路模型和电路定律”练习题
1-1说明题1-1图（a）、（b）中：（1）u、i的参考方向是否关联？（2）ui乘积表示什么功率？（3）如果在图（a）中u>0、i0、i>0，元件实际发出还是吸收功率？
（a） （b）
题1-1图
解
（1）u、i的参考方向是否关联？
答：(a) 关联――同一元件上的电压、电流的参考方向一致，称为关联参考方向；
(b) 非关联――同一元件上的电压、电流的参考方向相反，称为非关联参考方向。
（2）ui乘积表示什么功率？
答：(a) 吸收功率――关联方向下，乘积p = ui >0表示吸收功率；
(b) 发出功率――非关联方向，调换电流i的参考方向之后，乘积p = ui
元件发出功率。
（3）如果在图 (a) 中u>0，i
答：(a) 发出功率――关联方向下，u >0，i 0，i >0，功率p为正值下，元件实际吸收功率；
1-4 在指定的电压u和电流i的参考方向下，写出题1-4图所示各元件的u和i的约束方程（即VCR）。
（a） （b） （c）
（d） （e） （f）
题1-4图
解（a）电阻元件，u、i为关联参考方向。
由欧姆定律u = R i = 104 i
（b）电阻元件，u、i为非关联参考方向 由欧姆定律u = - R i = -10 i
（c）理想电压源与外部电路无关，故 u = 10V （d）理想电压源与外部电路无关，故 u = -5V
(e) 理想电流源与外部电路无关，故 （f）理想电流源与外部电路无关，故
i=10×10-3A=10-2A i=-10×10-3A=-10-2A
1-5 试求题1-5图中各电路中电压源、电流源及电阻的功率（须说明是吸收还是发出）。
解1-5图
（a） （b） （c）
题1-5图
解1-5图
解1-5图
解 （a）
由欧姆定律和基尔霍夫电压定律可知各元件的电压、电流如解1-5图（
a）
故 电阻功率 PR吸?ui?10?2?20W（吸收20W） 电流源功率 电压源功率
PI吸?ui?5?2?10W（吸收10W）
PU发?ui?15?2?30W（发出30W）
（b）由基尔霍夫电压定律和电流定律可得各元件的电压电流如解1-5图（b）
故 电阻功率 PR吸?12?3?45W（吸收45W） 电流源功率 P（发出30W） I发?15?2?30W电压源功率
PU发?15?1?15W（发出15W）
（c）由基尔霍夫电压定律和电流定律可得各元件的电压电流如解1-5图（c）
故 电阻功率 电流源功率 电压源功率
PR吸?15?3?45W（吸收45W） PI吸?15?2?30W（吸收30W）
PU发?15?5?75W（发出75W）
1-16 电路如题1-16图所示，试求每个元件发出或吸收的功率。
I1
（a） （b）
题1-16图
1-20 试求题1-20图所示电路中控制量u1及电压u。
u1
题1-20图
解：设电流i，列KVL方程
3
??1000i?10?10i?10u1?2
?3
??u1?10?10i?10u1
得：
u1?20Vu?200V
第二章“电阻电路的等效变换”练习题
2-1电路如题2-1图所示，已知uS=100V，R1=2k?，R2=8k?。试求以下3种情况下的电压
u2和电流i2、i3：（1）R3=8k?；（2）R3=?（R3处开路）；（3）R3=0（R3处短路）。
题2-1图
解：(1)R2和R3并联，其等效电阻R?
i1?
8
?4?,则总电流 2
us10050
??mA R1?R2?43
分流有
i150??8.333mA 26
50
u2?R2i2?8??66.667V
6i2?i3?
(2)当R3??,有i3?0
i2?
us100
??10mA
R1?R22?8
u2?R2i2?8?10?80V
(3)R3?0,有i2?0,u2?0
i3?
2-5用△―Y等效变换法求题2-5图中a、b端的等效电阻：（1）将结点①、②、③之间的三个9?电阻构成的△形变换为Y形；（2）将结点①、③、④与作为内部公共结点的②之间的三个9?电阻构成的Y
形变换为△形。
us100??50mA R12
a
b
题2-5图
①
①
R31
③
②
R2
R3
③
R14
R43
④
③
解解2-5图
解 （1）变换后的电路如解题2-5图（a）所示。 因为变换前，△中R12?R23?R31?9?
所以变换后，R1
1?R2?R3?3
?9?3?
故R(R12?6
ab?R1?2?9)//(R3?3)?3?12?6
?7?
（2）变换后的电路如图2-5图（b）所示。
因为变换前，Y中R1?R4?R3?9? 所以变换后，R14?R43?R31?3?9?27? 故 Rab?R14//(R43//3?R31//9)?7?
2-11 利用电源的等效变换，求题2-11图所示电路的电流i。
4
?
10V
题2-11图
解 由题意可将电路等效变 为解2-11图所示。
于是可得i1?
2.5i
?0.25A，i?1?0.125A 102
2-13 题2-13图所示电路中R1?R3?R4，R2?2R1，CCVS的电压uc?4R1i1，利用电源
的等效变换求电压u10。
uS
R4
解2-13图
题2-13图
解 由题意可等效电路图为解2-13图。 所以R?(R3?R4)//R2?2R1//2R1?R1 又由KVL得到 (R1i1?Ri1?
uS
=0.75uS 4
ucuR)?uS 所以i1?S R24R1
u10?uS?R1i1?uS?
2-14 试求题2-14图（a）、（b）的输入电阻Rab。
1
（a） （b）
题2-14图
解 （1）由题意可设端口电流i参考方向如图，于是可由KVL得到，
uab?R2i??u1?u1,
Rab?
u1?R1i
uab
?R2?(1??)R1 i
（2）由题已知可得
uab?R1i1?R2i2?R1i1?R2(1??)i1
Rab?
uab
?R1?(1??)R2 i1
第三章“电阻电路的一般分析”练习题
3-1 在以下两种情况下，画出题3-1图所示电路的图，并说明其结点数和支路数：（1）每
个元件作为一条支路处理；（2）电压源（独立或受控）和电阻的串联组合，电流源和电阻的并联组合作为一条支路处理。
（a） （b）
题3-1图
解:(1)每个元件作为一条支路处理时，图(a)和(b)所示电路的图分别为题解3-1图(a1)和(b1)。
图(a1)中节点数n?6，支路数b?11 图(b1)中节点数n?7，支路数b?12
(2)电压源和电阻的串联组合，电流源和电阻的并联组合作为一条支路处理时，图(a)和图(b)所示电路的图分别为题解图(a2)和(b2)。
图(a2)中节点数n?4，支路数b?8 图(b2)中节点数n?15，支路数b
?9
3-2 指出题3-1中两种情况下，KCL、KVL独立方程各为多少？
解：题3－1中的图(a)电路，在两种情况下，独立的KCL方程数分别为 (1)n?1?6?1?5 (2)n?1?4?1?3 独立的KVL方程数分别为
(1)b?n?1?11?6?1?6 (2)b?n?1?8?4?1?5
图(b)电路在两种情况下，独立的KCL方程数为 (1)n?1?7?1?6 (2)n?1?5?1?4 独立的KVL方程数分别为
(1)b?n?1?12?7?1?6 (2)b?n?1?9?5?1?5
3-7题3-7图所示电路中R1?R2?10?，R3?4?，R4?R5?8?，R6?2?，
uS3?20V，uS6?40V，用支路电流法求解电流i5。
u题3-7图
b?6 , 独立回路数为l?b?n?1?6?4?1?3 由KCL解 由题中知道n?4，
列方程：
对结点① i1?i2?i6?0 对结点② ?i2?i3?i4?0 对结点③ ?i4?i6?i6?0 由KVL列方程：
对回路Ⅰ 2i6?8i4?10i2??40 对回路Ⅱ -10i1?10i2?4i3??20 对回路Ⅲ -4i3?8i4?8i5?20 联立求得 i5??0.956 A
u
题3－7图
3-8 用网孔电流法求解题3-7图中电流i5。
解 可设三个网孔电流为i11、il2、il3，方向如题3-7图所示。列出网孔方程为
?(R2?R4?R6)il1?R2il2?R4il3??us6?
??R2il1?(R1?R2?R3)il2?R3il3??us3 ??Ri?Ri?(R?R?R)i?u
3l2345l3s3?4l1
il1?1i08?20l2?il3??40
?
il1?2i4420??10l2?il3?? ??8i?4i?20il3?20l2?l1
行列式解方程组为
20???10
?8
?10?824?4
20
20?8
?10?4024?4
?20??4880 20
?4??10
所以i5?i13?
?3?4880
???0.956A
?5104
3-11 用回路电流法求解题3-11图所示电路中电流I。
题3-11图
5V
解 由题已知，Il1?1A
???5Il1??5?5?30?Il2?30Il3?30
其余两回路方程为?
???20Il1?30Il2??20?30?Il3??5
Il2?3035?Il2??40l3?代人整理得 ????30I?5I0?15?Il3?l2l3?所以I?Il2?Il3?2?1.5?0.5A
2A
1.5A
3-12 用回路电流法求解题3-12图所示电路中电流Ia及电压Uo。
Ia
题3-12图
3-15 列出题3-15图（a）、（b）所示电路的结点电压方程。
GR
（a） （b）
题3-15图
i
iS7
i④(a)
题3-4图
③
(b)
isi
解：图(a)以④为参考结点，则结点电压方程为：
?G2?G3?un1?G2un2?G3un3?is2?is1
?G2un1??G2?G4?un2?is5?is2 ?G3un1??G3?G6?un3?is7?is5
图(b)以③为参考结点，电路可写成
??11?1
?u?????R?RR?n1Run2?is1?is534?4??2
?
?11??1
?u???Rn1?RR?un2??i
6??4?4
由于有受控源，所以控制量i的存在使方程数少于未知量数，需增补一个方
程，把控制量i用结点电压来表示有:
i?un1
R2?R3
3-21 用结点电压法求解题3-21图所示电路中电压U。
题3-21图
解 指定结点④为参考结点，写出结点电压方程
?un1?50V?11111?-u?(??)u?un3?0 ?n1n2552044???un3?15I
u
增补方程 I?n2
20
u150
可以解得 0.5un2??15?n2?
420510
un2??32V
0.3125电压 u?un2?32V。
第四章“电路定理”练习题
4-2 应用叠加定理求题4-2图所示电路中电压u。
50V
题4-2图
解：画出电源分别作用的分电路图
u①V－
(a)
(b)
题解4-2图
对(a)图应用结点电压法有
11?13650?1??u?? ??n1
8?210?8?24010?
解得：
u???un1?82.667V
1
对(b)图，应用电阻串并联化简方法，可得：
?10?40?
2??8??
10?4016usi?3??V 10?403???8???2?10?40?
u?2??
?usi8
??V 23
所以，由叠加定理得原电路的u为
u?u?1??u?2??80V
4-5应用叠加定理，按下列步骤求解题4-5图中Ia。（
1）将受控源参与叠加，画出三个分电路，第三分电路中受控源电压为6Ia，Ia并非分响应，而为未知总响应；（2）求出三个
?、Ia??、Ia???，Ia???中包含未知量Ia；??Ia???Ia???解出Ia。分电路的分响应Ia（3）利用Ia?Ia
题4-5图
4-9 求题4-9图所示电路的戴维宁或诺顿等效电路。
（a）
（b） 题4-9图
解：(b)题电路为梯形电路，根据齐性定理，应用“倒退法”求开路
'
电压uoc。设uoc?uoc?10V，各支路电流如图示，计算得
10
?1A10'
un2?un2?(2?10)?1?12V
'i5?i5?
'
un12
i4?i?2??2.4A
55'''
i3?i3?i4?i5?2.4?1?3.4A
'4
''
un1?un1?7?i3?un2?7?3.4?12?35.8V
un135.8
??5.967A66''
i1?i2?i3?5.967?3.4?9.367A
'i2?i2?
us?us'?9?i1'?un1?9?9.367?35.8?120.1V
故当us?5V时，开路电压uoc为
'
? uoc?Kuoc
5
?10?0.416V 12.1
将电路中的电压源短路，应用电阻串并联等效，求得等效内阻Req为
Req?[(9//6?7)//5?2]//10?3.505?
4-17 题4-17图所示电路的负载电阻RL可变，试问RL等于何值时可吸收最大功率？求此功
率。
L
题4-17图
解：首先求出RL以左部分的等效电路。断开RL，设 如题解4－17图（a）所示，并把受控电流源等效为受控电压源。由KVL可得
(2?2)i1?8i1?6
6
i1??0.5A
12
故开路电压 uoc?2i1?2i1?8i1?12i1?12?0.5?6V
把端口短路，如题解图（b）所示应用网孔电流法求短路电流isc，网孔方程为
? (2?2)i1?2isc?8i1?6?
?2i1?(2?4)isc?(2?8)i1?0
?
63
解得 isc??A
42故一端口电路的等效电阻 Req?
uoc6??4? isc2
画出戴维宁等效电路，接上待求支路RL，如题解图（c）所示，由最大功率传输定理知RL?Req?4?时其上获得最大功率。RL获得的最大功率为
Pmax
2uoc62???2.25W 4Req4?4
第五章“含有运算放大器的电阻电路”练习题
5-2 题5-2图所示电路起减法作用，求输出电压uo和输入电压u1、u2之间的关系。
Ru1+u2+
?
题5-2图
?
解：根据“虚断”，有： i ? ? i ? 0 得： i 3 ? i 1 , i 4 ? i 2 u0?u?u1?u?
?1???
故： R R
31
R2
u??u2?2? 而： R 1 ? R 2
R??
根据“虚短” 有： u ? u ? 2u 2
R1?R2
代入(1)式后得： R
u0?2?u2?u1? R1
5-6 试证明题5-6图所示电路若满足R1R4?R2R3，则电流iL仅决定于u1而与负载电阻RL
无关。
题5-6图
1和○2的选取如图所示，列出结点电压方证明：采用结点电压法分析。独立结点○
程，并注意到规则1，可得
((
111u?)un1?uo?1R1R2R2R11111??)un2?uo?0R1R2RLR4
应用规则2，有un1?un2，代入以上方程中，整理得
uo?R4(
111
??)un2 R3R4RL
(
1RRu?4?4)un2?1 R1R2R3R2RLR1
R2R3RL
u1
(R2R3?R1R4)RL?R1R3R4
un2R2R3
?u1 RL(R2R3?R1R4)RL?R1R3R4
故un2?
又因为iL?
当R1R4?R2R3时，
即电流iL与负载电阻RL无关，而知与电压u1有关。
5-7 求题5-7图所示电路的uo和输入电压uS1、uS2之间的关系。
题5-7图
1和○2的选取如图所示，解：采用结点电压法分析。独立结点○列出结点电压方程，并注意到规则1，得（为分析方便，用电导表示电阻元件参数）
(G1?G2)un1?G2uo?G1us1(G3?G4)un2?G4uo??G3us2
应用规则2 ，有un1?un2，代入上式，解得uo为
uo?
G1(G3?G4)us1?G3(G1?G2)us2
G1G4?G2G3
R2(R3?R4)us1?R4(R1?R2)us2
R2R3?R1R4
或为uo?
第六章“储能元件”练习题
6-8 求题6-8图所示电路中a、b端的等效电容与等效电感。
a
b
2H
a
8H
（a） （b）
题6-8图
Cab?
1
?5(
?3?220
?1)
?2.5F
Lab?8?
1?3
?88
?2
?10H
6-9 题6-9图中C1?2μF，C2?8μF；uC1(0)?uC2(0)??5V。现已知i?120e?5tμA，
求：（1）等效电容C及uC表达式；（2）分别求uC1与uC2，并核对KVL。
uCC2
题6-9图
解（1）等效电容
CC
C?12?1.6?F C1?C2
uC(0)= uC1(0)+uC2(0)=－10V 1t
u(t)= uC(0)+i(?)d? CC0
t 1
=－10+120?10－6e?5?d?－60 1.6?10
?
?
=－10?
120
?e?5?
1.6?(?5)
t0
?(5?15e?5t)V
(2)
t1 =－5+120?10－6e?5?d?－60
2?10
120 =－5??e?5?t0?(7?12e?5t)V2?(?5)
因此有： uC(t)= ut)+uC1(C2t
1t
uC1(t)= uC(0)+i(?)d?1
C1?01
uC2(t)= uC(0)+2
C2
?i(?)d?
t
?
t1
=－5+120?10－6e?5?d?－6?0
8?10120
=－5??e?5?t0?(?2?3e?5t)V
8?(?5)
6-10 题6-10图中L1?6H，i1(0)?2A；L2?1.5H，i2(0)??2A，u?6e
（1）等效电感L及i的表达式；（2）分别求i1与i2，并核对KCL。
?2t
V，求：
题6-10图
解（1）等效电感 解(2)
L1L2
?1.2H L?
L1?L2
i(0)= i1(0)+i2(0)=0V
1t
i(t)= i(0)+u(?)d? L0
1t?2?
=0+6ed? 1.20 6=0??e?2?t0?(2.5?2.5e?2t)A 1.2?(?2)
1t
i1(t)= i1(0)+?u(?)d?
L10
1t?2?
=2+?6ed?
60
6
=2??e?2?t0?(2.5?0.5e?2t)A
6?(?2)
1t
i2(t)= i2(0)+?u(?)d?
L20
1t?2?
=?2+6ed?
1.5?0
6
=?2??e?2?t0??2e?2tA
1.5?(?2)
?
?
因此有：i(t)= i1(t)+i2(t)
第七章“一阶电路和二阶电路的时域分析”练习题
7-1 题7-1图（a）、（b）所示电路中开关S在t=0时动作，试求电路在t=0+ 时刻电压、电流
的初始值。
10V
10V
uC
LuL
5
题7-1图
（a） （b）
解 (a):
Ⅰ： 求uC(0-)：由于开关闭合前(t
Ⅱ：求uC(0+)：根据换路时，电容电压不会突变，所以有：uC(0+)= uC(0-)=10V
Ⅲ： 求iC(0+)和uR(0+) ：0+时的等效电路如图(a1)所示。
iC?0????
10V
10?5
??1.5A10
uR?0???10?iC?0????15V
(a1)
换路后iC和uR 发生了跃变。
解 (b):
Ⅰ： 求iL(0-)：由于开关闭合前(t
iL?0????1A
5?5
Ⅱ： 求iL(0+)：根据换路时，电感电流不会突变，所以有： iL(0+)= iL(0-)=1A
Ⅲ： 求iR(0+)和uL(0+) ：0+时的等效电路如图(b1)所示。
uR?0????uL?0???5?iL?0???5?1?5ViR?0???iL?0???1A
(b1)
换路后电感电压uL 发生了跃变
7-8 题7-8图所示电路开关原合在位置1，t=0时开关由位置1合向位置2，求t ?0时电感电
压uL(t)。
66u
?15V
题7-8图
7-12 题7-12图所示电路中开关闭合前电容无初始储能，t=0时开关S闭合，求t ?0时的电
容电压uC(t)。
2V
uC
题7-12图
解：uC?0???uC?0???0
? t?? 时 i1?0
? uC????2V
用加压求流法求等效电阻
u?2i1?1??i1?4i1?
u
R??7?
i1
??RC?7?3?10?6?t21?10?6s 106t
????????21???uC?t??uC?????1?e??2?1?eV ??
????
7-17 题7-17图所示电路中开关打开以前电路已达稳定，t=0时开关S打开。求t ?0时的iC(t)，
并求t=2ms时电容的能量。
题7-17图
?
解：t >0时的电路如题图（a）所示。由图（a）知 uC(0?)?
12?1
?6 V 1?1
则初始值 uC(0?)?uC(0?)?6 V
t >0后的电路如题解图（b）所示。当t??时，电容看作断路，有 uC(?)?12 V
时间常数 ??R0C?(1?1)?103?20?10?6?0.04 s 利用三要素公式得
uC(t)?12?(6?12)e电容电流 iC(t)?C
?t0.04
?12?6e?25t V t?0
duC
?3?e?25t mA dt
t = 2 ms时
uC(2 ms)?12?6e电容的储能为
WC(2 ms)?
112
Cu
C(2 ms)??20?10?6?6.2932?396?10?6 J22
?25?2?10?3
?12?6e?0.05?6.293 V
7-20 题7-20图所示电路，开关合在位置1时已达稳定状态，t=0时开关由位置1合向位置2，求t ?0时的电压uL。
LuL
题7-20图
解：iL?0???iL?0????
8
??4A iL????i1?2 2
用加压求流法求等效电阻 4iL
????2i1?4i1?0 iL????1.2A
u??4?4?i1?2i1 R?
L0.1u
?0.01s ?10? ???
R10i1
?t
iL?t??iL?????iL?0???iL????e ?1.2???4?1.2??e ?1.2?5.2e?100tA
?t
0.01
?
??
7-26 题7-26图所示电路在开关S动作前已达稳态；t=0时S由1接至2，求t ?0时的iL。
6V
题7-26图
解：由图可知，t>0时
uC(0?)?4 V， iL(0?)?0 因此，t?0?时，电路的初始条件为
uC(0?)?uC(0?)?4 V iL(0?)?iL(0?)?C
duCdt
0?
?0
t>0后，电路的方程为
d2uCduC
?RC?uC?6 LC
dtdt2
设uC(t)的解为 uC?u'C?u''C 式中u'C为方程的特解，满足u'?6 V
根据特征方程的根 p??()2???1?j2
2L2LLC可知，电路处于衰减震荡过程，，因此，对应齐次方程的通解为
u''C?Ae??(t)sin(? t??)
式中??1,??2。由初始条件可得
uC(0?)?u'C(0?)?u''C(0?)?6?Asin??4
iL(0?)?C
duC
dt
0?
?C????Asin???Acos???0
解得
????63.43?
1
4?64?6A????2.236sinsin(63.43?)
故电容电压 uC(t)?u'C?u''C?6?2.236e?tsin(2t?63.43?) V 电流 iL(t)?C
7-29 RC电路中电容C原未充电，所加u(t)的波形如题7-29图所示，其中R?1000?，
duC
?CA2??2e? tsin? t?etsin2 t A dt
C?10μF。求电容电压uC，并把uC：（1）用分段形式写出；（2）用一个表达式写出。
C
（a） （b）
题7-29图
解：（1）分段求解。 在0?t?2区间，RC电路的零状态响应为 uC(t)?10(1?e?100t)
t?2 s时 uC(t)?10(1?e?100?2)?10 V
在2?t?3区间，RC的全响应为
uC(t)??20??10?(?20)?e?100(t?2)??20?30e?100(t?2) V
t?3 s时 uC(3)??20?30e?100?(3?2)??20 V
在3?t??区间，RC的零输入响应为
uC(t)?uC(3)e?100(t?3)??20e?100(t?3) V
(3)用阶跃函数表示激励，有
u(t)?10?(t)?30?(t?2)?20?(t?3) 而RC串联电路的单位阶跃响应为 s(t)?(1?e
?t
RC
)?(t)?(1?e?100t)?(t)
根据电路的线性时不变特性，有
uC(t)?10s(t)?30s(t?2)?20s(t?3) ?10(1?e
?100t
)?(t)?30(1?e
?100(t?2)
)?(t?2)?30(1?e
?100(t?3)
)?(t?3)
第八章“相量法”练习题
???100??150?V，其??50?30?V，U8-7 若已知两个同频正弦电压的相量分别为U12
频率f?100Hz。求：（1）u1、u2的时域形式；（2）u1与u2的相位差。
解：(1) ou1?
t???
2?ft?30o???628t?30o?V
u2?
t????
2?ft?150o???
628t?150o?180o???628t?30o?V
(2) U1?50?30，U2?100?30oV故相位差为??0，即两者同相位。
8-9已知题8-9图所示3个电压源的电压分别为ua?2cos(?t?10?)V、
.
o
.
ub?2cos(?t?110?)V、uc?2cos(?t?130?)V，求：
（1）三个电压的和；（2）uab、ubc；（3）画出它们的相量图。
a
b
c
题8-9图
c
解：ua,ub,uc的相量为
Ua?220?10，Ub?220??110，Uc?220?130o
.
o
.
o
.
(1) 应用相量法有
Ua?Ub?Uc?0
.
.
.
即三个电压的和 ua?t??ub?t??uc?t??0
(2)Uab?Ua?Ub?40oV
Ubc?Ub?Uc??80o (3)相量图解见题解8-3图
.
?..
?..
题解8-3图
?。 ??2?0?A。求电压U8-16 题8-16图所示电路中IS
j1?
题8-16图
??UU???解： IS?IR?IL??
RjXL?I?即U?S?11?
j
2?0?2??45?
?2?45?V
第九章“正弦稳态电路的分析”练习题
9-1
Z和导纳
?j1?
（a）
（b）
??rI
（c） （d）
题9-1图
解：（a）Z=1+
j2???j1?2
=1+=1?2j ?
j2?j1j1?2j11===0.2?j0.4 S
5Z1?2j
Y=
(b) (b) Z=1?
?j?(1?j)
=1?(1?j)?2?j ?
?j?(1?j)
Y=
112?j???0.4?j0.2S Z2?j5
(c)Y?
Z?
1140?j40?40?j401????0.025S
40?j4040?j4040?j4040?j4040
1
?40? Y
?，根据KVL，得 U??j?LI??rI???j?L?r?I? (d)设端口电压相量为U
?U
所以输入阻抗为 Z??j?L?r?
I
导纳 Y?
11?j?L?r??2S Zj?L?rr??l2
9-4 已知题9-4图所示电路中uS?sin(?t?30?)V，电流表A的读数为5A。?L=4?，
求电流表A1、A2的读数。
?US
题9-4图
解：求解XC
Zin?j?L?3//jXC?j4?
3jXC4XC?j(12?3XC)
?
223?jXC
3?XC
Zin?
(4XC)2?(12?3XC)2
32?XC
2
?
16 5
由分流定律?可解得I1?3A?I2?4A?
若XC=-0.878Ω时,同理可解得I1=4.799A,I2=1.404A。
可解得:XC??4?或XC??0.878?。
?
?US16??600
若XC??4??IS???5??970A
ZinZin
9-17 列出题9-17图所示电路的回路电流方程和结点电压方程。已知uS?14.14cos(2t)V，
iS?1.414cos(2t?30?)A。
（a）
（b）
?
?US
（c）
（d） 题9-17图
??200?0?V。试求R为何值时，电源U?发出的9-19 题9-19图所示电路中R可变动，USS
功率最大（有功功率）？
题9-19图
解：本题为戴维宁定理与最大功率传递定理的应用 1.求戴维宁等效电路
? j 10 Uoc?US?200?0V Z eq
?
?
2.由最大功率传递定理可知，
当R?Zeq?10?时，电源发出功率最大
US22
10??2000?4000W. Pmax?P20??Pmax?20
9-25把三个负载并联接到220V正弦电源上，各负载取用的功率和电流分别为：
；P2?8.8kW，I2?50A（感性）；P3?6.6kW，P1?4.4kW，I1?44.7A（感性）
。求题9-25图中表A、W的读数和电路的功率因数。 I2?60A（容性）
3Z3
题9-25图
解：根据题意画电路如题解9-25图。设电源电压为220?0?V
Z1?Z1??1,Z2?Z2??2,Z3?
Z3??3 根据P?UIcos?，可得
P14.4?103
cos?1???0.447
UI1220?44.7P28.8?103
cos?2???0.8
UI2220?50P36.6?103
cos?3???0.5
UI3220?60
即 ?1?63.42?,?2?36.87?,?3??60? 因此各支路电流相量为
??44.7??63.42?A?I?1
?（感性元件电流落后电压） ??I2?50??36.87A??
??60?60?A I3总电流
??I??I??I??44.7??63.42??50??36.87??60?60??90?j18?91.79??11.31?AI123电路的功率因数为
cos??cos?11.31??0.981
第十章“含有耦合电感的电路”练习题 10-4题10-4图所示电路中（1）L1?8H，L2?2H，M?2H；（2）L1?8H，L2?2H，
M?4H；（3）L1?L2?M?4H。试求以上三种情况从端子1?1?看进去的等效电感。
1
（a）
??
1
（b）
L2
1
（c）
1
（d） 题10-4图
解 以上各题的去耦等效电路如下图，根据电感的串并联公式可计算等效电感。
M
L1?M
L2?M
10-5 求题10-5图所示电路的输入阻抗Z（? =1 rad/s）。
1
1?
解 :
利用原边等效电路求解
等效阻抗为 ： ??M?2
Zeq?j?L1?（a）
Z22
11?j???0.2?j0.6??
（b）
1?j2
:
利用原边等效电路求解
等效阻抗为： Z eq ? 1 ? ? j 2
?? j5 ? j? ? ? 1 j ? ? j??
?
1
0.2?
1
1
解：去耦等效求解
j1
Zin???
等效阻抗为： 1
j1?
j1
j1?
（c） 去耦后的等效电感为：
Leq?1H
1题10-5图
???1rad/s
LeqC
Zin??,Yin?0
10-17 如果使100?电阻能获得最大功率，试确定题10-17图所示电路中理想变压器的变比n。
i
?
题10-17图
解 首先作出原边等效电路如解10-17图所示。 其中， R??n2RL?n2?10 又根据最大功率传输定理有
当且仅当
10?
n2?50时，10?电阻能获得最大功率 此时， n?
??
2.236? 1?50时，即n???2.236? n2此题也可以作出副边等效电路如b),
当10＝
10?电阻能获得最大功率
10-21 已知题10-21图所示电路中uS?2cos(?t)V，R1?10?，L1?L2?0.1mH，
M?0.02mH，C1?C2?0.01μF，??106rad/s。求R2为何值时获最大功率？并
求出最大功率。
CuS
R2
题10-21图
第十一章“电路的频率响应”练习题
11-6 求题11-6图所示电路在哪些频率时短路或开路？（注意：四图中任选两个）
C
2
CC
（a） （b） （c） （d）
题11-6图
解：（a） (b) 11
Z?
j?L?j?0Y?j?C?j?0 ?C?L
????0?
????0?
求电路的谐振频率f0、谐振时的电容电压UC和通带BW。
11-7 RLC串联电路中，L?50μH，C?100pF，Q?2?70.71，电源US?1mV。
解：f0?Q?
?2.25MHz
UC
??UC?S?70.7mVUS
11-10 RLC并联谐振时，f0?1kHz，Z(jω0)?100kΩ，BW?100Hz，求R、L和
C。
11-14 题11-14图中C2?400pF，L1?100μH。求下列条件下，电路的谐振频率ω0：
（1）R1?R2?
L1L1
；（2）R1?R2?。
C2C2
2
C2
题11-14图
第十二章“三相电路”练习题
12-1 已知对称三相电路的星形负载阻抗Z?(165?j84)?，端线阻抗Zl?(2?j1)?，中
性线阻抗ZN?(1?j1)?，线电压Ul?380V。求负载端的电流和线电压，并作电路
的相量图。
题解12-1图
解：按题意可画出对称三相电路如题解12－1图（a）所示。由于是对称三相电路，可以归结为一相（A相）电路的计算。如图(b)所示。
??U1?0??220?0?V，根据图（b）电路有 令UA
3
?U220?0?A? IA???1.174??26.98? A Z1?Z167?j85根据对称性可以写出
??a2I??1.174??146.98? A IBA
??aI??1.174?93.02? A ICB
负载端的'相电压为
????ZI??(165?j85)?1.174??26.98??217.90?0.275? UANA故，负载端的线电压为
????3U????30??377.41?30? V UABAN根据对称性可以写出
????377.41??90? V UB?C??a2UAB????377.41?150? V UC?A??aUAB
电路的向量图如题解12－1图（c）所示。
12-2已知对称三相电路的线电压Ul?380V（电源端），三角形负载阻抗Z?(4.5?j14)?，
端线阻抗Zl?(1.5?j2)?。求线电流和负载的相电流，并作相量图。
解：本题为对称三相电路，可归结为一相电路计算。先将该电路变换为对称Y－Y电路，如题解12－2图（a）所示。图中将三角形负载阻抗Z变换为星型负载阻抗为 ZY
?
11
Z??(4.5?j14)?(1.5?j4.67) ? 33
题解12－2图
??U1?0??220?0?V，根据一相（ A相）计算电路（见题解12－1图 令UA
3
?为 （b）中），有线电流IA
??U220?0A?? I??30.08??65.78? A A
Z1?ZY3?j6.67
根据对称性可以写出
??a2I??30.08??185.78? A IBA
??aI??30.08?54.22? A ICA
利用三角形连接的线电流与相电流之间的关系，可求得原三角形负载中的相电流，有
????1I??30??17.37??35.78? A IABA
????a2I????17.37??155.78? A 而 IBCAB????aI????17.37?84.22? A ICAAB电路的相量图如题解12－2图（b）所示。
12-5 题12-5图所示对称Y―Y三相电路中，电压表的读数为1143.16V，Z?(15?j)?，
（1）图中电流表的读数及线电压UAB；（2）三相负载吸收的功率；Zl?(1?j2)?。求：
（3）如果A相的负载阻抗等于零（其他不变），再求（1）（2）；（4）如果A相负载开路，再求（1）（2）。（5）如果加接零阻抗中性线ZN?0，则（3）、（4）将发生怎样的变化？
A
B
题12-5图
N?
C
???0，可以归结为一相（A相）电解：图示电路为对称Y－Y三相电路，故有UNN路的计算。
根据题意知UA?B??1143.16V，则负载端处的相电压UA?N?为 UA?N??而线电流为
I1?故电源端线电压UAB为
UA?B?1143.16
??660 V 3UA?N?660??22 A（电流表读数） Z30
UAB?U1?Z1?ZI1??32.232?22?1228.2 V
?为 ??220?0?V，则线电流I(1）令UAAN
??U220?0AN?? I??6.1??33.69? A A
Z30?j20
故图中电流表的读数为6.1A。 （2）三相负载吸收的功率为
2
P?3IAR?3?6.12?30?3349 W
（3）如果A相的负载阻抗等于零（即A相短路），则B相和C相负载所施加的电压均为电源线电压，即N?点和A点等电位，而
? UAB?
??30??380?30? V 3UAN
???U???aU??380??30?V UACCAAB此时三相负载端的各相电流为
?U380?30? AB? IN?B???10.54??3.69? A
Z30?j20?? INC
?U380??30? AC
???10.54??63.69? A Z30?j20
??I???I???10.54??3.69??10.54??63.69?IANBNC ?18.26??33.7 A
?
这时图中的电流表读数变为18.26A。 三相负载吸收的功率变为：
22
P?2IN.5 W ?BR?2?(10.54)?30?6665
? （4）如果图示电路中A相负载开路，则B相和C相负载阻抗串联接入电压UBC中，而
??a2U??a2U??30??380??90? V UBCABAN此时三相负载中的各相电流为
??0 IA
?U380??90?BC?? IBN???ICN????5.27??123.69?V 2Z2?(20?j20)这时图中的电流表读数为零。 三相负载吸收的功率为
22
P?2IB.4 W N?R?2?(5.27)?30?1666
12-6 题12-6图所示对称三相电路中，UA?B??380V，三相电动机吸收的功率为1.4kW，其
功率因数??0.866（滞后），Zl??j55?。求UAB和电源端的功率因数??。 A
Z
B
C
题12-6图
第十三章“非正弦周期电流电路和信号的频谱”练习题
13-7 已知一RLC串联电路的端口电压和电流为
u(t)?[100cos(314t)?50cos(942t?30?)]V
i(t)?[10cos(314t)?1.755cos(942t??3)]A
试求：（1）R
、L、C的值；（2）?3的值；（3）电路消耗的功率。
解：RLC 串联电路如图所示，电路中的电压 u(t) 和电流 i(t) 均为已知，
分别含有基波和三次谐波分量。
(1)由于基波的电压和电流同相位，所以，RLC 电路在基波频率下发生串联谐振。故有 R?
Um1100
??10? Im110
且 XL1?Xc1?X1 即 ?1L?
1
?X1(?1?314rads) ?1C
而三次谐波的阻抗为
Z3?R?j3?1L?j
18
?10?j(3X1?X1)?10?jX1 3?1C331
Z3的模值为
U850
Z3?2?(X1)2?m3??28.49?
3Im31.755解得 X1为
X1?(28.492?102)?
9
?10.004?
64
.
故
L?C?
X1
?1
?
10.004
?31.86mH314
11
??318.34?F?1X1314?10.004
（2）三次谐波时，Z3的阻抗角为
8X13?3??arctan2.668?69.450 10而
?3??u3??i3??300??3 则
?3??300??3??99.450 （3） 电路消耗的功率 P 为
P?
13-9 题13-9图所示电路中uS(t)为非正弦周期电压，其中含有3?1和7?1的谐波分量。如果
要求在输出电压u(t)中不含这两个谐波分量，问L、C应为多少？
uS
11
?100?10??50?1.755cos69.450?515.4W 22
题13-9图
解：根据图示结构知，欲使输出电压u(t) 中不含3?1 和 7?1 的谐波分量，就要求该电路在这两个频率时，输出电压u(t) 中的3次谐波分量和7次谐波分量分别为零。
若在 3?1 处 1H 电感与电容 C 发生串联谐振，输出电压的3次谐波
U3?0 ，由谐振条件，得
3?1?
1L1C
,C?
19?L1
2
1
?
19?
21
若在 7?1 处 1F 电容与电感 L 发生并联谐振，则电路中7次谐波的电流
I7?0 ，电压 U7?0， 由谐振条件，得
7?1?
1LC1
,L?
149?12C1
?
1
49?12
也可将上述两个频率处发生谐振的次序调换一下，即在3?1 处，使 L 与 C1 发生并联谐振，而在 7?1 处，使 L1 与 C 发生串联谐振，则得
L?
19?12
C?
1
2
49?1
第十六章“二端口网络”练习题
16-1 求题16-1图所示二端口的Y参数、Z参数和T参数矩阵。（注意：两图中任选一个）
1
12?
12
1
2?
2
（a） （b）
题16-1图
解： 对 (a)，利用观察法列出Y参数方程：
1 ? ? 1 ? 1??UU??jUj U1 ?21 ?2 I 1 ? j?L?L?L 1 1 1????????j?I??U?U?j?CU?jU?C?? 2 1 2 2 1 ? U 2
j?L?L ?L??
? 1 1 ?
j 则Y参数矩阵为： ??j?L??LY?? 11????j?j??C?? ? ?L????L??
同理可列出Z参数方程： 1 ? 1 1 ? ???j?LI?? I? ???j??UI?L?I?I?11112 j? C ? ? C ? j ? 2 C
1??1?1?
U ? 2 ? I 1 ? I 2 ? I 1 ? I 2
j?Cj?Cj?C
则Z参数矩阵为： ??1?1?
j?L??? ???Cj?C???Z?? 1 1 ??
? j?C j?C?
??
列出T参数方程： 将式2代入式1得：
??j?LI??U???j?Lj?CU??I??U?UU1 21 2 1 2 2
??
??
??
??
??j?LI??1??2LCU22
?
?
?
?
?? I 1 ? j ? C U ? 2 ? I2
则T参数矩阵为： 2
?1??L ? T ? LC j ? ??
? j ? C 1 ?
16-5 求题16-5图所示二端口的混合（H）参数矩阵。（注意：两图中任选一个）
1
1
21
2
2? 1
2?
（a） （b）
题16-5图
解：对图示（a）电路，指定端口电压u1,u2和电流i1,i2及其参考方向。由KCL，KVL和元件VCR，可得
u1?(i1?u1)?2u2 经整理，则有
u1?i1?u2
2
而 i2?u2?2u2??u2 故可得出H参数矩阵
? H??2
??0
1?? ?1??
g?
2S。16-15 试求题16-15图所示电路的输入阻抗Zi。已知C1?C2?1F， G1?G2?1S，
G
2? 2
题16-15图
解：图示电路中，当回转器输出端口接一导纳时Y2(s)?G2?sC2(端口2?2?开路)，根据回转器的VCR，可得出从回转器输入端口看进去的输入导纳为
g2g2
Y1(s)??
Y2(s)G2?sC2
所以，该电路的输入阻抗Zin(s)为
Zin(s)????
G1sC1?Y1(s)G1
g2
sG1?
G2?sC2
2
?s2?2s?5 s?s?4
篇6：内科学造血系统疾病习题及参考答案2
30.在我国成年巨幼细胞性贫血患者中
a.以缺乏叶酸为主
b.以缺乏维生素b12为主
c.以缺乏维生素c为主
d.叶酸、维生素b12同时缺乏为主
e.叶酸缺乏与维生素b12缺乏不分主次
答案：a
31.正常成人骨髓红系造血的代偿能力是
a.1～2倍
b.4～8倍
c.6～8倍
d.8～10倍
e.8～12倍
答案：c
32.溶血性黄疸的尿液检查结果是
a.尿胆原阴性，尿胆红素阴性
b.尿胆原阳性，尿胆红素阴性
c.尿胆原阴性，尿胆红素阳性
d.尿胆原阳性，尿胆红素阳性
e.尿胆原阳性，尿胆红素强阳性
答案：b
33.关于溶血的概念，错误的是
a.溶血是指红细胞寿命缩短，破坏加速
b.有溶血存在，就一定有贫血
c.有溶血存在，不一定有黄疸
d.溶血有血管内与血管外之分
e.红细胞本身正常也会发生溶血
答案：b
34.应首选脾切除治疗的溶血性贫血是
a.自身免疫性溶血性贫血
b.遗传性球形细胞增多症
c.阵发性睡眠性血红蛋白尿
d.丙酮酸激酶缺乏症
e.海洋性贫血
答案：b
35.诊断溶血最可靠的指标是
a.网织红细胞比例升高
b.血清结合珠蛋白减少
c.红细胞寿命缩短
d.骨髓幼红细胞显著增生
e.外周血中出现少量幼红细胞
答案：c
36.溶血的直接证据是
a.急剧发生的贫血
b.网织红细胞明显增多
c.外周血出现幼红细胞
d.骨髓幼红细胞显著增生
e.血清游离胆红素增多
答案：e
37.支持慢性血管内溶血的项目是
a.血清结合珠蛋白降低
b.血清游离胆红素增高
c.尿胆原排泄量增加
d.尿含铁血黄素阳性
e.骨髓幼红细胞比例增多
答案：d
38.应首选糖皮质激素治疗的贫血是
a.海洋性贫血
b.遗传性球型红细胞增多症
c.阵发性睡眠性血红蛋白尿
d.自身免疫性溶血性贫血
e.再生障碍性贫血
答案：d
