一．从句的分类
从句不能单独成句，但它也有主语部分和谓语部分，就像一个句子一样。所不同在于，从句须由一个关联词引导。根据引导从句为主不同大概可分为：主语从句、表语从句、宾语从句、同位语从句、定语从句和状语从句6类。前四类由于主语从句、表语从句、宾语从句及同位语从句在句子的功用相当于名词，所以通称名词性从句；定语从句功能相当于形容词，称为形容词性从句；而状语从句功能相当于副词，称为副词性从句。状语从句还可以分为条件状语从句、原因状语从句、地点状语从句、目的状语从句、让步状语从句、比较状语从句、方式状语从句、结果状语从句和时间状语从句。
二.各从句在句子中的位置以及用法：
(1)主语从句：在句子中充当句子主语的从句叫主语从句。位于谓语动词之前。通常由that,whether以及疑问连词引导。一般情况下,常用it替代主语从句,而将主语从句移到句尾。如：When we should start is still a question. (我们该在什么时候开始还是个问题呢。)
(2)表语从句：在句子中作连系动词的表语的从句,它位于主句中的系动词之后。
例如：That is why he did not come to school yesterday. / It is because you are so clever.
(3)宾语从句：在句子中作及物动词或介词的宾语。
①基本形式：（主句＋）连词+从句主语+从句谓语+...
② 关于宾语从句连词的选择：
若从句来源于一个陈述句,那么,连词用that,在口语中that可以省略;
例如：They believe that the computer will finally take the place of human beings.(他们相信计算机终将代替人类。) (从句本来就是陈述句)
若从句来源于一个一般疑问句,连词则用if 或whether;
例如：I wonder whether I should say something for him to the headmaster. (我不知道是不是该为他在校长跟前说点什么。
若从句来源于一个特殊疑问句,则连词就是疑问词(如what,who,where,when等)
例如： He asked me where he could get such medicine. (他问我在哪儿能搞到那样的药。) (从句来源于特殊问句Where can he get such medicine? )
③ 宾语从句的时态问题：如果主句是现在时,从句则用现在某一时态,甚至可以用过去时； 如主句是过去时,从句则相应地使用过去某一时态,遇到客观真理时仍然用现在时。
如：I think I will do better in English this term. (我想本学期我的英语会学得好点。)
The teacher asked the boy if the earth is round. (老师问那个男孩地球是不是圆的。)
④ 下列结构后面的从句一般也作为宾语从句看待：
be sorry / afraid / sure / glad +that从句,如：I’m sorry I’m late. (对不起,我迟到了。) / I’m afraid he isn’t in at the moment. (恐怕他此刻不在家。)
(4) 定语从句：在复合句中作定语用修饰句子中某一名词或代词的从句叫定语从句。
① 定语从句的位置：放在名词或代词的后面。如：The man who has an umbrella in his hand is my uncle. (手上抓了一把雨伞的人是我的叔叔。)
② 语法术语的改变：被修饰的名词或代词称为先行词；引导定语从句的连接词称为关系词,其中that、which、who称为关系代词,where、when、how称为关系副词。
③ 关系代词或关系副词的作用：
关系代词who、whom 和whose指人,分别在从句中作主语、宾语和定语。which指物that多指物, 有时也指人,它们在从句中可以作主语或宾语。定语从句中关系代词作从句宾语时可以省略。This is the thief (that/who/whom) we have been looking for these days. (这个就是我们近日一直在找的小偷。) / Please find a room which is big enough for all of us to live in. (请找一间足够大能住下我们全体的房间。)
关系副词when或where引导定语从句时,它们在从句中分别作时间状语和地点状语。如：This is the room where they had a quarrel a week ago. (这是一个星期前他们吵架的房间。) / I can never forget the day when I first saw you. (我永远不会忘记第一次见到你的日子。)
④ 性定语从句和非性定语从句。性定语从句在句中不能省略,否则主句意思就不完整。非性定语从句和主句之间往往用逗号分开,这种从句是一种附加说明,如果从句子中省去,也不致于影响主句的意思。如：She spent the whole evening talking about her latest book, which none of us had heard of. (她一个晚上都在谈论她最近的书,我们一个人都没有听说过那本书。)
[注解]
1、关系代词只能用that的情况：当先行词是指事物的不定代词(all, anything等),或先行词部分含有最高级,或含有序数词时,不能用其他的关系代词,只能用that. 如：All that Lily told me seems untrue. (Lily告诉我的话似乎不真实。) / Can you give me anything that has no sugar inside? (能不能给我点里面没有糖的东西？) / This is the first two-story bus that runs in our city. (这是第一辆运行于我市的双层公交车。)
2、关系代词在从句中作主语时一般用who(指人)、that(指物),而不用that指人或用which指物。 如：Do you know the woman who is weeping in the corner? (你认识那个在角落里哭泣的女人吗？) / Do not tell me any words that have nothing to do with me. (跟我无关的话,请一个字也不要说。)
3、关系代词作从句的宾语时,常用which或whom,较少使用that或who,而且,关系代词常常省略。如：Tom’s father was the first parent whom our teacher talked to. (Tom的父亲是我们老师第一个谈话的人。)
4、当关系代词紧跟在介词后面时,必须用which或whom,而当介词移到句尾时,则又可以使用that或who. 如：This is the room in which Miss Li once lived. (= This is the room Miss Li once lived in.) (这是李小姐曾经居住过的房间。)
(5) 状语从句：在复合句中作状语,其位置可以在主句前或主句后。状语从句可以分为时间、地点、原因、目的、结果、比较、让步、条件等几种。状语从句由从属连接词引导。
时间状语从句通常由when ,as ,while, after, before, since, as soon as ,since, till (until), while, whenever 等引导。时间状语从句一般放在句首或句尾,特别注意,时间状语从句不允许使用将来时,而应该用现在时替代。如： When you finish the work, you may go out to play with Sam. (你完成工作就可以出去和Jim一起玩了。) / I won’t leave until Mum comes back. (妈妈回来了我才会走。)
地点状语从句通常由 where, wherever等引导。如：Go back where you came from! (哪里来还滚到哪里去！) / I will never forget to catch the thief who stole my necklace wherever he may be. (我永远也不会忘记去抓住那个偷我项链的贼,无论他会在哪里。)
原因状语从句通常由because, since, as等引导,一般放在句首或句尾。如：He went abroad because his father had found a good university for him. (他出国了,因为他父亲给他找了一所好大学。)
目的状语从句通常由so that..., so...hat..., in order that... 等引导,往往放在句尾,从句中通常含有can / could / may / might等情态动词。如：He got up earlier so that he could catch the first train. (他起身更早为的是赶上第一班车。)
结果状语从句通常由 so that..., so...that... 等引导,放在句尾。结果状语从句一般表示已经发生的事情,故多为过去时态。如：He lost so many bikes that he decided never to buy a new one. (他丢了那么多辆自行车,他决定再也不买新车了。)
比较状语从句通常由as, than, as (so)...as等引导,一般省略从句的谓语部分,只剩下名词或代词(用主格或宾格均可)。如：Jane is much taller than I/me. (Jane比我高多了。) / I don’t have as many books as you (do). (我书没有你多)
让步状语从句通常由though (although), as, even if( even though), however, whatever等引导。如：Even if you pay the debt(债务) for me, I will not thank you because it has nothing to do with me. (即使你替我还了债我也不会感谢你,因为它与我毫无关系。) / He wears a T-shirt though it is very cold. (他穿了一件T恤衫,尽管天很冷。)
条件状语从句通常由if, unless, as long as等引导,条件状语从句一般放在句首或句尾,特别注意,时间状语从句不允许使用将来时,而应该用现在时替代。You will certainly fail in the coming final exams unless you work much harder. (即将来到的期末考试你肯定考不及格,除非你更用功。) / If it doesn’ t rain tomorrow, we shall go hiking. (如果明天不下雨我们就要去徒步旅行。)
[注意] 1、because与so；(al)though与but；if与so不可以同在一个句子中成对出现。
2、时间、条件、原因,让步状语从句放在句首时需要用逗号与主句隔开。
三．注意区分定语从句和同位语从句
1．定语从句修饰先行词，它和先行词是修饰关系；同位语从句说明先行词的具体内容，是补充说明的关系
(1) The plane that has just taken off is for London. 定语从句
(2) The fact that he has been dead is clear. 同位于从句
2．定语从句由关系代词或者关系副词引导，关系词在句中充当成分，有时可以省略；同位语从句主要由that引导，在句中一般不做成分；句子也可以由when, where, how, why, whether, what等词引导，充当成分
(1) The news he told me is true.
(2) The news that he has just died is true.
(3) The problem that we are facing now is how we can collect so much money. 定语
(4) The problem how we can collect so much money is difficult to solve.
3. 同位语从句和先行词一般可以用be动词发展成一个完整的句子，而定语从句不可以
(1) The idea that we could ask the teacher for advice is wonderful.
(2) The idea was that we could ask the teacher for advice.
(3) The fact that the earth moves around the earth is known to all. 同位语
(4) The fact is that the earth moves around the earth.
四。练习
（一）名词性从句
1. Go and get your coat. It's _______ you left it.
A. there B. where C. there were D. where there
2. _______ the sports meet will be held depends on the weather.
A. Whenever B. If C. Whether D. That
3. The problem is_______ he has enough time.
A. if B. whether C./ D. that
4. He made a promise_______ he would help me.
A. what B. when C. that D. which
5. I remember_______ this used to be a quiet village.
A. how B. when C. where D. what
6. They lost their way in the forest and _____ made matters worse was that night began to fall.
A. that B. this C. what D. which
7. He told me the news ____ the Queen would visit China the next month.
A. that B. which C. when D. when
8. When the holidays were drawing near, I asked my American friends ___ was the best way to travel in the United States.
A. that B. what C. such D. that
9. He was lucky enough to sell his car for exactly ______.
A. where he had paid for it B. what he had paid for it
C. what he was paid for it D. which he had paid for it
10. Sometimes we are asked ______ we think the likely result of an action will be.
A. that B. what C. which D. whether
11. They have not made any decision on ______ they are going to do to deal with the waste and control pollution.
A. that B. which C. if D. what
12. --- Do you know him?
--- Yes, but I can’t remember ________I met him for the first time.
A. where B. what C that D. if
13. --- Do you know _____ Mr. Black’s address is.
--- He may live at No. 18 or No. 19 of Bridge Street. I'm not sure of _____.
A. what; which B. where; which C. where ; what D. what; where
14. This old computer must have been of great use to _______ did the scientific research.
A. those B. when C. whoever D. whomever
15. _______ all the inventions have in common is _____they have succeeded.
A. What; what B. That; that C. What; that D That; what
16. --- I rang you at about ten, but there was no reply.
--- Oh, that was probably ____ I was seeing the doctor.
A. when B. why C. what D. that
17. Maria has to baby-sit. That’s______ she can't come with us.
A. why B. how C. when D. what
18. ____ surprised me most was ______ they had finished it so quickly
A. What, what B. That, that C. What, that D. That, what
19. The reason why she couldn’t come to the meeting was_____ she had not been invited.
A. because B. which C. that D. why
20. In some countries, ____ is called "equality" does not really mean equal rights for all people.
A. which B. that C. what D. one
（二）定语从句
1. We should learn from those ______ are always ready to help others.
A. who B. whom C. they D. that
2. Mr. Herpin is one of the foreign experts who ____ in China.
A.works B. is working C. are working D. has been working
3 Tom is the only one of the students who ______ to Shanghai. .
A.have gone B. have been C. has been D. had gon
4. I, ______ your good friend, will try my best to help you out.
A. who is B. who am C. that is D. which am
5. The old man has two sons, ______ are lawyers.
A.both of them B. both of who C. both of whom D. both of they
6. He is a man of great knowledge, ____ much can be learned.
A. in whom B. about whom C. from whom D. of whom
7 Do you know the man ______ just now?
A. to who I nodded B. I nodded to C. whom I nodded D. whom I nodded to him.
8. The man ____ has gone to Japan.
A.whom I told you B. that I told you
C. whom I told you about him D. I told you about
9. Please pass me the dictionary ______ cover is black.
A. which B. its C. whose D. which of
10. The radio set ______ last week has been out of order.
A.I bought B. I bought it C. which I bought it D. what I bought
11. All the apples ______ fell down from the tree were eaten up by the pigs.
A. which B. / C. that D. they
12. I can tell you ______ he told me last week.
A. all which B. all what C. that all D. all that
13. This is the biggest lab ______ we have ever built in our university.
A. which B. what C. that D. where
14. Is oxygen the only gas ______ helps fire burn?
A. that B. / C. which D. what
15. Air, ______ we breathe every day, is around us all the time.
A. that B. / C. which D. it
16. This is the museum ______ we saw an exhibition the other day.
A. that B. which C. where D. in that
17. This museum is ______ you visited the other day.
A. that B. which C. where D. the one
18. This is the museum ______ you saw the other day.
A. that B. where C. in which D. in that
19. It is the third time __ late this month.
A.that you arrived B.when you arrived C. that you’ve arrived D. when you’ve arrived
20. It was in 1969 ___ the American astronaut succeeded in landing on the moon.
A. that B. which C. in which D. when
（三）状语从句
1. After the war，a new school building was put up ________ there had once been a theatre.
A. that B. where C. which D. when
2. ____ he took part in the competition, he won a second prize.
A. For the first time B. At a time C. At one time D. The first time
3. I would appreciate it _______ you call back this afternoon for the doctor’s appointment.
A. until B. if C. when D. that
4. I had just started back for the house to change my clothes _____ I heard the voices.
A. as B. after C. while D. when
5. The class went on with the story _____ they had left it before the holiday.
A. where B. which C. in which D. when
6. The company has a free long-distance telephone number _____ customers may call with any questions they have about its products.
A. although B. as C. even if D. so that
7. --- Is Mr. Smith in the office?
--- Yes，________ he is in charge of the office，he must be there.
A. since B. however C. whether D. for
8. Someone called me up in the middle of the night，but they hung up ________ I could answer the phone.
A. as B. since C. until D. before
9. --- Don’t look down upon Bob. He has his own advantages.
--- Oh, yes. ________ others are weak, he is strong.
A. If B. When C. Where D. Though
10. The day must be breaking, _____ the birds have begun singing.
A. because B. as C. for D. since
11. John may phone tonight. I don’t want to go out ________ he phones.
A. as long as B. in order to C. in case D. so that
12. ____others say, the expert is sure that his theory is correct
A. No matter B. It doesn’t matter C. Whatever D. What
13. Many places are flooded by heavy rainfalls, so they can’t walk _______ they like these days.
A. when B. whenever C. where D. wherever
14. His father began to work ______ his childhood.
A. since B. before C. as early as D. while
15. The roof fell _____ he had time to dash into the room to save his baby.
A. before B. as C. after D. until
16. --- The thread of my kite broke and it flew away.
--- I had told you it would easily break ________it was the weakest
A. when B. where C. unless D. since
17. The crowd started cheering ______ he rose to speak.
A. as B. since C. till D. where
18. I had worked here ______ you came here. But I shall leave for England ______.
A. before long, before long B. before long; long before
C. long before, before long D. long before; long before
19. Scientists say it may be five or ten years _____ it is possible to test this medicine on human patients.
A. since B. before C. after D. when
20. ___ the Internet is bringing the distance between people, it may also be breaking some homes or will cause other family problems.
A. When B. If C. As D. While
Lecture Twelve 理科班英语语法篇（十二） 从句
名词性从句参:
1~20: BCBCB CABBB DAACC AACCC
定语从句参：
1—5 ACCBC 6—10 CBDCA 11—15 CDCAC 16—20 CDACA
状语从句参：
1~20: BDBDA DADCC CCDDA BACBD 下载本文
