定语从句

定语从句【知识简介】名词或代词由一个从句来修饰，该从句即定语从句。

定语从句一般后置，但as引导的修饰全句的定语从句可以
前置。

引导定语从句的词有关系代词that, which, who, whom, whose, as 等以及关系副词when, where, why等。

关系代词或关系副词放在被修饰的名词或代词（又叫做先行词）和定语从句之间起联系作用，同时又作定语从句中的一个成份。

【要点难点】1) that和which的用法区别只用that的情况：①先行词由最高级修饰时，如the best work that I can do。

②先行词由序数词修饰时，如the second book that I bought。

③先行
词由the last, the only, the same, the very等修饰时。

④先行词是不定代词all, anything, everything, little, much, nobody, nothing等时，如anything that he does; all that I can do now等。

⑤先行词有any, no, all等限定词时，如all the words that I’ve learned。

⑥先行词为词组，该词组既含人又含物时，如the city and the people that I visited。

只用which的情况：①在非限定性定语从句中（定语从句前有逗号）。

②介词后。

请看that和which的使用例句：? It’s the best film that’s ever been made on the subject of madness. 这是以精神病为题材而拍摄的影片中最好的一段。

? Shakespeare is the greatest poet that England has ever had. 莎士比亚是英
国最伟大的诗人。

（本句中先行词虽是人，但由于前面也有形容词最高级修饰，仍用that较好）? Take the first opportunity that offers. 抓住第
一个出现的机会。

? He is the last person that one would suspect. 人们最
不可能怀疑他。

? Man is the only creature that is gifted with speech. 只有人类具有语言的天赋。

? A fool sees not the same tree that a wise man sees.
一个傻瓜看到的树和一个聪明人看到的树不一样。

? Those were the very words that he said at the meeting. 这些就是他在会上说的原话。

?
All that glitters is not gold. 闪光的并不都是金子。

? Anything that you have to say had better be said in each other’s presence. 有话最好当面说。

? There’s still much that is to be done. 仍然有很多事要做。

? I have changed my mind. Nothing that you say will change it. 我已经改变了主意，无论你说什么也无法改变它。

? Nobody that was there could convince her of her mistake. 这那儿没有一个人能使她明白她的错误。

? Every paper that you read gives the same story. 你看的每份报纸都报道同样的新闻。

?
I still can’t forget the places and the people that I visited during last summer vacation. 我仍然难以忘怀去年暑假我见到的地方和人。

2) 关系代词（that, which, who, whom等）和关系副词（when, where等）的用法区
别①关系代词在定语从句作主语、宾语或表语，而关系副词在定语从句中作状语。

②分析时主要从动词的及物性或有无介词来考虑。

看
如下对比例句：①This is the factory where my father once worked. 这是我父亲曾工作过的工厂。

（worked是不及物动词，不接宾语，所以不用which/that。

where相当于in the factory）This is the factory which/that my father once worked in.（worked in的宾语是factory，故用关系代词
which/that）②I will never forget the days which/that I spent in the wood near our village. 我忘不了我在我村边小树林里度过的日子。

（the days
是spent的宾语）I will never forget the days when I spent my holidays with my grandparents. 我忘不了我和我的祖父母一起度假的日子。

（spent的宾语是holidays，不是the days）I will never forget the small village where
I spent my holidays. 我忘不了我度假的小村庄。

（与上句一样，spent的宾语是my holidays）③Is this the school which/that you visited the other day? 这是你几天前参观过的学校吗？（the school作visited的宾语）Is this the school where you visited your teacher the other day? 这是你几天
前拜访你老师的学校吗？（visited在定语从句中有自己的宾语your teacher，所以不用that/which）3) those who和he who句型两个常用句型。

He who常用于谚语中。

请看例句：? He who doesn’t reach the Great Wall is not a true man. 不到长城非好汉。

? God helps those who help themselves. 上帝帮助自强的人。

? He who insists on seeing with perfect clearness before he decides never decides. 坚持一切看清楚之后才做决定的人永远也做不了决定。

? He was a bold man who first ate an oyster. 第一个吃牡蛎的人是勇敢的人。

4) whose的用法whose是关系限定词，既可以指人也可以指物，即既可以说“某人的”，也可以说“某物的”。

? Fortune never helps the man whose courage fails. 运气永远不会帮助丧失勇气的人。

? That's the man whose house has burned down. 那就是那位房屋烧毁的人。

? Have you noticed the house whose windows are closed now? 你注意到了那家窗户关着的房子吗？? He’s written a book whose name I have completely forgotten. 他写了一本书，书名我完全忘记了。

? Above the trees are the mountains, whose magnificence the river faithfully reflects on the surface. 在树林的高处是山，其壮丽的景色完全映照在河面上。

注：在正式文体中，指物时，whose往往用of which表示。

of which可放在被修饰的名词之前或之后，而whose只能放在被修饰的名词之前。

例如：The house whose windows/of which the windows/the windows of
which are broken is unoccupied.（那间窗户破了的房屋没人居住。

）whose 前有时有介词。

? The teacher in whose class my daughter is studying is a kindhearted man. 我女儿所在的那位老师心地善良。

? Michel Croz, with whosehelp, Woolworth climbed to the mountain top, was one of the prefessional guides. 米歇尔?克罗兹是职业向导之一，在他的帮助下伍德沃斯攀登到了山顶。

? Then we had a chance to talk with that tall man, from whose accent we at once knew that he came from Hunan Province. 后来我们有机会和那个高个子说话，我们从他的口音迅速知道他是个湖南人。

5) 限制性定语从句和非限制性定语从句的区别限制性定语从句和非限制性定语从句的区别：限制性定语从句是先行词（即被修饰词）不可缺少的定语，限制性定语从句前不用逗号隔开；非限制性定语从句只是对先行词的附加说明，如果去掉，先行词所述对象仍很清楚，非限制性定语从句前常用逗号隔开。

这里有两个例句及分析：Those who want to go camping please tell the monitor. 想去野营的人请告诉班长。

（定语从句who want to go camping在句中不可少，否则先行词those不知道指谁，也就变得无意义，因此它是限制性定语从句。

）Football, which is a very interesting game, is played all over the world. 足球风靡全世界，它是一项很有趣的运动。

（定语从句which is a very interesting game 只是对意义已很明确的football作一个补充说明，因此它是非限制性定语从句。

）注意，非限制性定语从句可以用关系代词which, who, whom, whose, as及介词+which/whom等引导，也可以用关系副词when, where 引导，但不能用that引导。

另外，非限制性定语从句中的关系代词或关系副词是不能省略的。

6) whom的用法只有作定语从句中的宾语时才
能用whom；介词后用whom不用who。

口语中whom前无介词时可用that或who代替。

? My brother, whom you met the other day, has gone abroad. 前几天你遇见过的我的那个兄弟，出国去了。

? I have a few friends whom I could ring to see if they are free. 我有几个朋友，我可以打电话去联系，看看他们是不是有时间。

? You have many people around you who are kind to you but whom you will soon forget. 你周围有许多对你好的人，但你都会很快忘记他们。

? There came a lot of children, most of whom I didn’t know. 来了许多孩子，大多数我都不认识。

7) 介词＋which/whom引导的定语从句如果关系代词which/whom本身在定语从句中充当一个介词或介词短语的宾语的时候，有时可以将介词直接放在which/whom的前面，这样就产生了“介词＋关系代词”及“名词或代词＋介词＋which/whom”或“复合介词＋which/whom”等的结构。

? I know the man to whom you talked just now. 我认识你刚才与之说话的那个人。

? Life is a flower of which love is honey. 人生是花朵，爱情是花蜜。

? He was educated at the local grammar school, after which he went on to Cambridge. 当在当地的一所中学上学，此后就去上了剑桥大学。

? It’s a family of five children, all of whom are studying music. 这一家有五个孩子，他们都在学音乐。

? In the attic we found some apples, none of which was fit to eat. 在阁楼里我们发现了一些苹果，其中没有一个能吃的。

?
I have three brothers, all of whom have gone abroad. 我有三个兄弟，他们都出国了。

? Soon they spotted a mountain, on top of which stood a temple. 不久他们发现了一座山，山顶上有一座庙宇。

8) why引导的定语从句关系副词why用在reason之后，只引导限制性定语从句，why在从句
中作状语，表示原因。

? Give me the reason why you should be interested in his affairs. 告诉我你为什么竟对他的事这样感兴趣。

? The reason why she was ill was that she had eaten bad meat. 她生病的原因是她吃了变质的肉。

? That is the reason why he raised the question. 这就是他所以提出问题的原因。

注意：有时reason后不一定是why引导的定语从句。

如下列句子中，reason后接的是which/that引导的定语从句，这是因为，reason在定语从句中作主语或宾语。

? Is this the reason which/that the chairman gave at the meeting? 这就是主席在会上所给的理由吗？? I really can’t understand the reason that/which he explained. 我实在无法理解他所解释的理由。

9) where引导定语从句有时修饰一些具有抽象意义的表示地点的名词，如situation, point, position等等。

? If you are ever in a situation where someone starts shooting, drop to the ground. 如果你遇到有人要射击的情况就摔倒在地上。

? But after a few days’ stay they got to the point where they could read each other's thoughts. 不过呆了几天之后，他们到了一个彼此能理解相互想法的阶段。

? It got to the point where I couldn't remember any of the reasons I loved him. 到那时候，我无法记起我爱他的任何理由了。

10) the way后的定语从句The way后的定语从句用in which引导，in which可以用that代替，而that又可以省略。

所以，表达“某人做某事的方法”有三种形式：1. the way in which somebody does something 2. the way that somebody does something 3. the way somebody does something. 11) which指代前面的句中的内容which 的这一用法只能以非限定性定语从句出现。

? Jenny was late for school a third time during the week, which made her teacher very angry. 詹妮一周
内第三次迟到了，这使得她老师很生气。

? He left early, which was wise. 他早早地离开，那是很明智的。

? He suddenly became wealthy, which changed his whole mode of life. 他忽然变得富有了，这改变了他整个的
生活方式。

? He often helps me with my lessons, which is kind of him. 他经常在功课方面帮助我，真是感谢他。

12) which作关系限定词的情况which作为关系限定词时，其本身代替前面所陈述的内容。

? She asked me to see the doctor, which advice I took at once. 她要我去看医生，我立
即采纳了她的建议。

? He is studying economics, which knowledge is very important today. 他正在攻读经济学，这门知识在今天是非常重要的。

? He believes in students’ doing more homework, which idea I am quite opposed to. 他相信要让学生做更多的家庭作业，我非常反对这个观点。

which的这种用法常伴随介词而用。

常见的词组形式有by which means, during which time, in which case, for which mistake, for which reason等等。

? She may have missed the train, in which case (=if this happens) she won't arrive for another hour. 她也许没赶上火车，如果那样的话，她一小时是到不了的。

? I called him by the wrong name, for which mistake I apologize. 我叫错了他的名字，为此我道歉。

? He didn’t feel well that morning, for which reason he didn’t attend school. 那天早晨他感到不舒服，因此，他没去上学。

? Tom spent four years in college, during which time he learned French. 汤姆在大学上了四年学，在这段时间里，他学会了法语。

13) as用法关系代词as引导定语从句有两种形式。

（1）as引导
一个非限制性定语从句修饰一个分句，as代表该分句所表达的整个概念或其中一部分的概念。

as定语从句可置于句首、句中或句尾；as本身在
从句中充当主语、宾语及表语。

（2）用于as … as, the same … as, so … as, such … as等结构中。

as用法的第一种情况：? As is known to all, the earth moves around the sun. 众所周知，地球围绕太阳旋转。

? He must be an African, as may be seen from the colour of his skin. 他准是个非洲人，
这可以从他的肤色看得出来。

? If he comes late, as is usual, for another time, we’ll not receive him. 如果他再一次像以往那样迟到，我们就不接
待他了。

? She is a fine singer, as her mother used to be. 她是个很出色的歌唱家，像她的母亲当年一样。

? As you will find out, all is now settled. 你会发现，现在一切都解决了。

? Helen is somewhat crazy, as everyone could see. 海伦有些神经错乱，这种情况每个人都看得出。

注意这一类的as表面上看好像和which代替全句时的用法相似，但as引导的定语
从句的最大特点是它的意思多侧重于表达“（正）像……、（正）如……”及类似的意思。

一般说来，当关系代词在从句中作be动词的主语或一
般动词的宾语时，which和as可交替使用；当关系代词在从句中作一般动词（非be动词）的主语时，只能用which；as可置于句首、句中，而which则不能。

例如：? He was late for school, as/which was usual with him. 他上学迟到了，他经常这样。

? He saw the girl, as/which he had hoped (he would). 他见到了那位姑娘姑娘，正像他希望的那样。

? He saw the girl, which delighted him. 他见到了那位姑娘，这使得他很开心。

（句中的which不能用as代替，因为从句中的delighted是非be动词）? As has been said before, grammar is not a set of dead rules. 正如上面所说的那样，语法不是一套死的规则。

（句中的As不能用Which代替，因为此定语
从句置于句首）as用法的第二种情况：? There’s as good fish in the sea as ever came out of it. 海里有的是鱼；天涯处处有芳草。

? Here is so big a stone as no man can lift. 这是一块没人能搬动的大石头。

? Her manner and attitude toward him were quite the same as they had always been. 她对他的举止和态度和往常是完全相同的。

? He does not possess such a mind as is necessary to a scientist. 他缺乏科学家所必须具备的头脑。

? Such food as they gave us was scarcely fit to eat. 他们给我们的食物很不适合吃。

? A man such as he will surely succeed. 像他这样的人是肯定会成功的。

? I haven’t much money but you can use such as I have. 我钱不多，可你能用我所有的钱。

? Such as you see is all we have. 你所见到的就是我们所有的东西。

14) 介词+whom/which + to do的类定语从句结构的不定式用法? This is a useful tool with which to cut steel. 这是可以用来切割钢材的工具。

? Can you recommend someone from whom to learn how to use the software? 你能推荐一个可以向他讨教使用这一软件的人吗？? It’s not a room in which to live comfortably. 这不是可以舒适居住的房间。

这一结构的介词位置固定，不可移到动词之后，如第一句中的with which to cut steel不可改成which to cut stell with。

15) 嵌入式定语从句有一种定语从句，在其从句中的主语和谓语之间有一个插入语如I think。

这一种定语从句叫做嵌入式定语从句。

嵌入的分句的谓语动词常常是think, believe, guess, imagine, say, suppose, be sure, doubt
等等。

? She offered a suggestion which she said would interest you. 她提出一个她说一定会引起你兴趣的建议。

? He wrote letters to every person
and organization that he believed might be able to help. 他写信给每个人和每个组织，他相信可能有帮助。

? That is the engineer who I think is the right man chosen for the job. 那位就是我认为适合被选派做这项工作的工程师。

高中定语从句专项练习题及详解50题
1.The place _______interested me most was the Children's Palace.
A. Which
B. where
C. what
D. in which
2.Do you know the man _______?
A. whom I spoke
B. to who spoke
C. I spoke to
D. that I spoke
3.This is the hotel _______last month.
A. which they stayed
B. at that they stayed
C. where they stayed at
D. where they stayed
4.Do you know the year ______the Chinese Communist Party was founded?
A. which
B. that
C. when
D. on which
5.That is the day ______I'll never forget.
A. which
B. on which
C. in which
D. when
6.The factory ______we'll visit next week is not far from here.
A. where
B. to which
C. which
D. in which
7.Great changes have taken place since then in the factory _______we are working.
A. where
B. that
C. which
D. there
8.This is one of the best films _______.
A. that have been shown this year
B. that have shown
C. that has been shown this year
D. that you talked
9.Can you lend me the book ______the other day?
A. about which you talked
B. which you talked
C. about that you talked
D. that you talked
10.The pen ______he is writing is mine.
A. with which
B. in which
C. on which
D. by which
11.They arrived at a farmhouse, in front of ______sat a small boy.
A. whom
B. who
C. which
D. that
12.The engineer ______my father works is about 50 years old.
A. to whom
B. on whom
C. with which
D. with whom
13.It there anyone in your class ______family is in the country?
A. who
B. who's
C. which
D. whose
14.I'm interested in ______you have said.
A. all that
B. all what
C. that
D. which
15.I want to use the same dictionary ______was used yesterday.
A. which
B. who
C. what
D. as
16.He isn't such a man ______he used to be.
A. who
B. whom
C. that
D. as
17.He is good at English, ______we all know.
A. that
B. as
C. whom
D. what
18.Li Ming, ______to the concert enjoyed it very much.
A. I went with
B. with whom I went
C. with who I went
D.I went with him
19.I don't like ______ as you read.
A. the novels
B. the such novels
C. such novels
D. same novels
20.He talked a lot about things and persons ________they remembered in the school.
A. which
B. that
C. whom
D. what
21.The letter is from my sister, ______is working in Beijing.
A. which
B. that
C. whom
D. who
22.In our factory there are 2,000 workers, two thirds of ____are women.
A. them
B. which
C. whom
D. who
23.You're the only person ______I've ever met ______could do it.
A. who;/
B./; whom
C. whom;/
D./; who
24.I lost a book, ______I can't remember now.
A. whose title
B. its title
C. the title of it
D. the title of that
st summer we visited the West Lake, ______Hangzhou is famous in the world.
A. for which
B. for that
C. in which
D. what
26.I have bought such a watch _______ was advertised on TV.
A. that
B. which
C. as
D. it
27.I can never forget the day _______ we worked together and the day ______ we spent together.
A. when; which
B. which; when
C. what; that
D. on which; when
28.The way ______he looks at problems is wrong.
A. which
B. whose
C. what
D./
29.This is the reason ______he didn't come to the meeting.
A. in which
B. with which
C. that
D. for which
30.This machine, ______for many years, is still working perfectly.
A. after which I have looked
B. which I have looked after
C. that I have looked after
D. I have looked after
31.The reason ______he didn't come was ______he was ill.
A. why; that
B.that;why
C. for that;that
D.for which;what
32.He is working hard, ______will make him pass the final exam.
A.that
B.which
C.for which
D.who
33.That is not the way ______I do it.
A./
B.which
C.for which
D.with which
34.I have two grammars, ______are of great use.
A. all of which
B. either of which
C. both of that
D. both of which
35.I want to use the same tools _______used in your factory a few days ago.
A. as was
B. which was
C. as were
D. which
36.My neigh bours used to give me a hand in time of trouble, _______ was very kind of them.
A. who
B. which
C. that
D. it
37.This is the magazine _______ I copied the paragraph.
A. that
B. which
C. from that
D. from which
38.He is not such a man _______ would leave his work half done.
A. that
B. which
C. who
D. as
39. You can depend on whatever promise _______ he makes.
A. /
B. why
C. when
D. whose
40. Smoking, _______ is a bad habit, is, however, popular.
A. that
B. which
C. it
D. though
41. --- Did you ask the guard _______ happened?
--- Yes, he told me all _______ he knew.
A. what; that
B. what; what
C. which; which
D. that; that
42. I shall never forget those years _______ I lived on the farm with
the farmers, _______ has a great effect on my life.
A. when; who
B. that; which
C. which; that
D. when; which
43. The number of the people who _______ cars _______ increasing.
A. owns; are
B. owns; is
C. own; is
D. own; are
44. During the days ________, he worked as a servant at the Browns.
A. followed
B. following
C. to follow
D. that followed
45. Is oxygen the only gas _______ helps fire burn?
A. that
B. /
C. which
D. it
46. The clever boy made a hole in the wall, _______ he could see
_____ was going on inside house.
A. which; what
B. through which; what
C. through that; what
D. what; that
47. Is _______ some German friends visited last week?
A. this school
B. this the school
C. this school one
D. this school where
48. John got beaten in the game, _______ had been expected.
A. as
B. that
C. what
D. who
49. I have bought two ballpens, _______ writes well.
A. none of them
B. neither of them
C. neither of which
D. none of which
50. All that can be eaten _______ eaten up.
A. are being
B. has been
C. had been
D. have been
参考答案及解析
1. A. which用作关系代词，在定语从句中作主语。

2．C. "和谁讲话”要说speak to sb. 本题全句应为Do you know the man whom I spoke to.。

whom是关系代词，作介词to的宾语，可以省略。

3. D. where是关系副词，表示地点，在定语从句中作地点状语。

4. C. when是关系副词，表示时间，在定语从句中作时间状语。

5．A. which是关系代词，在从句中作forget的宾语。

其他几个答案都不能作宾语。

6．C. 解析同第5题。

7. A. 解析见第3题。

8. A. 本句话的先行词应该是films,因此，关系代词that是负数概念，其谓语动词应用复述的被动语态have been shown。

如果句中的one前面使用了定冠词the，则the one应该视为先行词。

9. A. “谈到某事物”应说talk about sth.。

about是介词，其后要用which 作宾语，不能用that。

10. A. with which是"介词+关系代词"结构,常用来引导定语从句.with 有"用"的意思,介词之
后只能用which,不能用that. with which在定语从句中作状语,即he
is writing with a pen.
11. C. in front of which 即in front of a farmhouse. In front of which在从句中作状语.
12. D. with whom引导定语从句.with whom放在从句中即为:my f ather works with the engineer.
13. D. whose引导定语从句,在从句中作主语family的定语.
14. A. that引导定语从句,因为先行词是all,所以只能选用that引导.
15. D. the same……..as是固定用法, as引导定语从句时,可以作主语,
宾语或表语.在本句话中,as作从句的主语.
16. D. such……… as是固定用法,as引导定语从句时,可以作主语,宾语
或表语.在本题中,as作表语.
17. B. as作关系代词可以单独用来引导非限制性定语从句。

这时a s所指代的不是主句中某个名词，而往往指代整个主句的含义。

as在从句中可以作主语、宾语。

从句可放在主句后，也可置于主句前。

在本句中,as作宾语.
18. B. Li Ming enjoyed it very much是主句,with whom I went t
o the concert是定语从句.with whom放在从句中为:I went to the conc ert with Li Ming.
19. C. as引导定语从句时通常构成such…as或the same…as固定搭配，其中such和same修饰其后的名词，as为关系代词，指代其前的名词引
导定语从句。

as在从句中可以作主语、表语或宾语。

Such修饰单数名词时,要用such a……..,本题中such books, such直接修饰复数名词.
20. B. things和persons是先行词.当定语从句要修饰的先行词是既表示人,又表示物的名词时,其关系代词要用that.
21. D. who引导非限制性定语从句,who作从句的主语.
22. C. two thirds of whom 即:two thirds of the 2,000 workers.
23. D. 先行词person后有两个定语从句,第一个从句省略了关系代词whom.因为, whom作从句中met的宾语,可以省略.第二个从句who c ould do it.who在从句中作主语,不可省略.
24. A. whose title引导非限制性定语从句,whose title也可以说成t he title of which
25. A. for which 引导定语从句,使用介词for,是来自于从句中的固定短语be famous for "以……..而闻名".
26. C. 当先行词被such修饰时,引导定语从句的关系代词要用as. As在本从句中作主语.
27. A. 两个先行词the day都是表示时间的名词,但第一个空白处要填的关系词在从句中作状语,因此要用关系副词when. 第二个空白处要填的关系词在从句中作动词spent的宾语,因此要用关系代词which或th at来引导定语从句.
28. D. 在way、distance、direction等词后的定语从句中，常用that 来代替“in (或其他介词)+which”、when或where，而that常可省略。

29. D. for which在定语从句中作原因状语,可用why 来替代.
30. B. which I have looked after 构成一个非限制性定语从句.
31. A. The reason why… was that….已成为一种固定句型，这一句中的why和that不能随意换位，也不能将that改成because，尽管that这个词在译文中可能有“因为”的含义。

32. B. 非限制性定语从句常用which引导,which表示前句话的整个含义.
33. A. 解释见28题.
34. D. 主句中的two表明不能选A.从句中的are表明不能选B. bot
h of which用来引导非限制性定语从句.
35. C. as引导定语从句时通常构成such…as或the same…as固定搭配，其中such和same修饰其后的名词，as为关系代词，指代其前的名词引导定语从句。

as在从句中可以作主语、表语或宾语。

本题中as作从句
的主语.
36. B. 非限制性定语从句常用which引导,which表示前句话的整个含义.
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37. D.
38. D. 解析见35题.
39. A. he makes是定语从句, 从句前省略了关系代词that.
40. B. which is a bad habit 非限制性定语从句.
41. A. what happened是宾语从句. all 之后that he knew是定语从句.先行词是all,所以关系代词只能用that.
42. D. years是表示时间的名词,用when引导定语从句,是因为when
在从句中作时间状语.第二个空选用which,引导一个非限制性定语从句.
43. C. 本句话的定语从句是who own cars. 其先行词是people,因此,定语从句的谓语动词要用复数的own。

本句话主句的主语是The number of指“…..的数目”，是单数概念。

因此，主句的谓语动词要用is。

44. D. that followed是定语从句，关系代词that在从句中作主语。

45. A. 先行词gas被only修饰，关系代词要用that，而不用which。

46. B. through which引导定语从句，through which即through the hole,在定语从句中作状语。

What引导的是see的宾语从句，并作从句的主语。

47. B. 为便于理解，改写本句话：This is the school that some Germanfriends visited last week. 不难看出，作表语的the school是先行词。

that引导了定语从句，因为that同时又作visited的宾语，所以被省略了。

其它选项结构不对。

48. A. 解释见35题。

49. C. 因为是two ballpens, 并且定语从句的谓语writes是单数概念。

因此，C是正确选项。

50. B. 本句话中，主句的主语是all,为抽象概念。

因此，其谓语应用单数的has been。

关系代词that引导定语从句，并在从句中作主语。