[介词的选择]在介词+关系代词中，介词的选择受以下限制：（1）以从句中动词；形容词；名词与介词的固定搭配而定；[高考考例]2. In the dark street, there wasn’t a single person _____ she could turn for help. [MET 1992]A. thatB. whoC. from whomD. to whom[思路点拨]答案为D. turn to sb for help 为固定搭配表示“求助于某人”（2）以先行词与从句中的动词关系及所表达的含义而定或以先行词在定语从句中的作用与含义而定。
[考例]1. The medicine of science, ______ progress has been very rapid lately, is perhaps the most important of all the science.A. to whichB. in whichC. whichD. with which[思路点拨]答案为B.从句主谓结构搭配为：progress has been rapid in, 这里的in意为“在某方面”，相当于rapid progress has been made in the science of medicine.[考例]2. The professor made his first speech _____ he talked about some subjects the students were interested.A. thatB. whichC. in whichD. of which[小结]关键词：介词的选用与从句主谓结构的搭配有关。
[跟踪实练]1. I don’t think the number of people ____ this happens is very large.A. whomB. to whomC. on whomD. which2. The school has 3,000 students, _____ 1,800 are men.A. whoseB. of whomC. thatD. of which3. Recently I bought an ancient Chinese vase, ______ was very reasonable.A. which priceB. the price of whichC. its priceD. the price of whose4. The gentleman ______ you told me yesterday proved to be a thief.A. whoB. about whomC. whomD. with whom5. She wrote a lot of stories for children, _____ this is one example.A. in whichB. of whichC. among themD. of them6. He offered us a lot of money _____ we couldn’t buy these machines.A. without whichB. with thatC. with whichD. without that7. Mary, ____ for help, has gone to England.A. who I can go toB. whom I can goC. to whom I can goD. I can go to8. Now we have very powerful telescopes _____ we can study the skies.A. in whichB. with whichC. through whichD. by which9. The man ______ she was married was a soldier.A. whomB. to whomC. with whomD. who10. Tom, ____ I went to the concert, is a friend of mine.A. whomB. whoC. with whomD. whose答案为:1. B 2. B 3. B 4. B 5. B 6. A 7. C 8. C 9. B 10. C常见的有以下几种情况:1. where=in/on which 例:This is the room where / in which he lives.这是他住的房间。
I can see the playground where / on which they do sports.我能看见他们进行运动的操场。
2. when= on/in/at which 例:I still remember the year when/ in which I joined the Party.我仍然记得入党的那一年。
I still remember the day when/on which I joined the Party. 我仍然记得入党的那一天。
I still remember the hour when/at which the rocket was launched.我仍然记得那个火箭发射的时刻。
3. why=for which 例:This is the reason why / for which he was killed.这是他被杀害的原因。
⑴用who代替whom,用that代替which时,介词不能提前。
例:He's the boy who I learned English from.这是我向他学英语的男孩。
This should be the place that Tom sent the parcel to. 这应是汤姆送包裹的地方。
⑵当whom、which省去时介词不能提前。
例:Is he the boy you went there with?他是和你一起去那儿的男孩吗?This is the room he lived in. 这是他住过的房间。
⑶当whom, which作为含有介词的动词短语的宾语时,介词一般来说不能拆开提前。
例:You're the very man whom I'm looking for. 你正是我在找的那个人。
This is the program which he listened to. 这就是他听过的节目。
再看下面几种结构答案补充(一)介词+whose引导的定语从句whose引导定语从句时,可出现创新句型:介词+whose引导定语从句。
解这种定语从句时需弄清从句的动词与先行词、whose后边的名词及定语从句主语之间的关系,并发挥合理想象,不难发现其中正确的逻辑关系。
例:She is the girl to whose father I talked yesterday. 她就是昨天我和其父亲谈话的女孩。
He is the boy for whose boss I work. 他就是我为其老板打工的男孩。
(二)复杂介词+whom/which引导定语从句I stay at the hotel at the back of which is a small garden. 我住在后面有一座花园的旅馆。
(三)数词(不定量数词)/ 含所属关系名词+of whom/which引导定语从句。
例:She has many books, only one of which is interesting. 她有许多书,只有一本是有趣的本单元的语法重点是区别和运用几个表示原因的连词和词组：because, since, as, due to, due to the fact that等。
一、连词的主要用法。
连词是一种在句子之间，短语之间以及名词等其他词语之间起连接作用的虚词，它不能单独作句子的成分。
连词按其意义可分为并列连词和从属连词两大类，对连词的考查主要也是对并列连词和从属连词基本用法的考查。
本单元主要练习使用用来表示双方互为因果，前因后果或前果后因的连词，亦可用这种连词引导原因状语从句，常用的连接词有：because, since, as等。
二、 because, because of, since, as, for, due to, due to the fact that的联系与区别。
1. 联系：以上的词和词组都表示原因，意为“因为；由于”。
2. 区别(1) because通常表示说话人认为这种理由或者原因是听话人所不知道的，后接从句，既可以位于句首也可以放在句中使用，但不与so连用。
如： He didn't attend the meeting because he had too much work to do.(2) because of 与because所表达的意思一样，但其后接单词或短语。
如：He didn't go to school because of illness.(3) since表示的原因是人们已知的事实，常译作“既然”。
如：Since he can't answer this question, you'd better ask someone else.(4) as表示原因与since差别不大，只是语气更弱,多译作“由于”。
如：As I haven't seen the film, I can't tell you what I think of it.(5) for表示因果关系时，只能放在主句之后，不能放在句首。
而且经常是对主句补充说明理由或推断原因。
如：It rained last night, for the ground is wet.⑹ due to是说明原因的短语，to 为介词，因此due to 后接名词或名词性短语。
如：Due to the benefits of garlic, he decided to eat it more often.(7) due to the fact that 与due to意思相同样，但due to the fact that后接从句。
如： We stayed inside the house due to the fact that the weather was cold.单项选择。