博主的话：定语从句一直是高中英语教学中的大难点，对于有些同学定语从句就像是盲区，怎么讲都不能理解。分析传统的定语从句讲义，往往都是以关系词来分类，再分析每个关系词可以有什么用法，记忆点显得多而且杂。对于刚接触定语从句的学生来说实在有点措手不及。针对这个情况，我对定语从句的讲义进行了新的整理。把它根据先行词的情况及运用来分类。既强调了初学定语从句时找准先行词的重要性，也使得记忆更加有规律，更加简单明了。定语从句是英语语法的难点之一，其中非限制性定语从句更令同学们难以把握。我从非限制性定语从句与限制性定语从句的区别出发，讨论关于非限制性定语从句的常见易错题目的解答方法。
　　1. 引导限制性定语从句时，关系代词which可以与that互换；但引导非限制性定语从句时，只能用which。
　　例1She heard a terrible noise,______ frightened her.
　　A. that  B. which  C. what  D. who
　　例2She heard a terrible noise
　　______ frightened her.
　　A. that  B. /      C. what  D. who
　　解析：例1意为：“她听到一个可怕的声音，这使她感到恐惧。”that不能用于引导非限制性定语从句，故选B。例2意为：“她听到了一个使她恐惧的可怕声音。”引导修饰noise的限制性定语从句可以用which或that来引导,故选A。
　　2. 先行词为reason时，限制性定语可以用why或for which来引导；非限制性定语从句则只能用for which来引导。
　　例3I had told them the reason, ______ I didn’t attend the meeting.
　　A. for which B. at which C. for whom D. why
　　例4I had told them the reason ______ I didn’t attend the meeting.
　　A. when B. which C. why D. for that
　　解析： 例3意为：“我早已把理由告诉他们，于是我没有出席会议。”先行词为reason时，非限制性定语从句应用for which引导，故选A。例4意为：“我已经把为什么没有出席会议的原因告诉他们。”the reason why...是常见搭配，答案为C。
　　3. 引导限制性定语从句的关系代词在从句中担任宾语时可以被省略；但引导非限制性定语从句的关系代词即使作宾语也不能省略。
　　例5He was eager to go to the hospital to see his stepmother,______ he loved and respected as his own mother.
　　A. as   B. which   C. /   D. whom
　　解析：本句意为：“他急于去医院看望他的继母，他像对待亲生母亲一样孝敬她。”关系代词whom引导非限制性定语从句并作宾语，不能被省略，故选D。
　　4．引导限制性定语从句时并作从句宾语的关系代词whom可以用who来代替；但在非限制性定语从句中，whom就不能用who替换。
　　例6Do you know Tom, _____ we talked about?
　　A. which B. that C. whom D. who
　　例7The American journalist ______ the announcer mentioned in the news broadcast is said to have been killed by the gangsters. Which of the following is wrong?
　　A. who B. whom C. whose D. /
　　解析： 例6意为：“你认识汤姆吗? 我们谈到过他。”应选C。例7意为：“播音员在新闻广播中提到的那位美国记者据说已遭歹徒杀害。下列哪一项是错误的？”关系代词作mentioned的宾语且指人时，可用who/whom/that，在限制性定语从句中可省略，故C是错的。
　　5．当非限制性定语从句修饰整个主句时，其关系代词只能用as ，不能用which。此时非限制性定语从句可置于主句之前、之后或之中。
　　例8______ I expected, he didn’t believe me.
　　A. Which B. As C. That D. When
　　解析： 本句意为：“正如我所预料的那样，他不相信我的话。”非限制性定语从句修饰整个主句，应用as引导，故答案为B。
　　例9Mary was late for school,______ often happened.
　　A. as B. for which C. that D. why
　　解析：本句意为：“玛丽上学迟到了，这是常有的事。”根据句意，关系代词as引导的非限制性定语从句修饰前面的主句，其位置非常灵活，故答案为A。
　　6. 由“介词+关系代词”引导非限制性定语从句，关系代词指代整个主句时，不能用as，只能用which。
　　例10He bought the car for more than $20,000,______ his father was angry.
　　A. about that B. with as C. when D. with which
　　解析：本句意为：“他花两万多美元买了这辆车，他父亲对此很生气。”which位于介词with的后面，指代前面的主句，故答案为D。
　　
　　【练习题】
　　1. He was very rude to the customs officer, ______ of course made things even worse.
　　A. which B. whom C. what D. who

解析：
　　2. The old lady,______ had been killed in the war, was given help by the local government.
　　A. all her children B. all of her children C. all of whose children D. whose all children

解析：
　　3. Living in the central Australia desert has its problems,______ getting water is not the least.
　　A. of which B. for what C. as D. whose

解析：
　　4. It rained hard yesterday, ______ prevented me from going to the park.
　　A. that B. it C. as D. which

解析：
　　5. The youngest nurse has worked for 30 days in the SARS hospital, ______ she spent her 19th birthday． A. that B. which C. where D. and

解析：
　　6. Recently I bought an ancient Chinese vase,______ was very reasonable.
　　A. which price B. the price of which C. its price D. the price of whose

解析：
　　7. The Beatles,______ many of you are old enough to remember, came from Liverpool.
　　A. what B. that C. how D. as

解析：
　　8. There are libraries for grownups and libraries for children ______ you can borrow books to read.  A. which B. whom C. from which D. from whom

解析：
　　9. The owner of the cinema needed to make a lot of improvements and employ more people to   keep it running,______ meant spending tens of thousands of pounds.
　　A. who B. that C. as D. which

解析：
　　10.______ is known to everybody, the moon travels round the earth once every month.
　　A. It B. As C. That D. What

解析：
　　11. Look out! Don’t get too close to the house,______ the roof is under repair.
　　A. whose B. which C. of which D.what

解析：
　　12. We saw several natives advancing towards our party, and one of them came up to us,______ we gave some bells and glasses.
　　A. to whom B. to which C. with whom D. with which

解析：
　　13.______ has been announced, we shall have our final examination next month.
　　A. That B. What C. It D. As

解析：
　　14. Alice received an invitation from her boss,______ came as a surprise.
　　A. it B. that C. which D. he

解析：
　　15. The weather turned out to be very good, ______ was more than we could expect.
　　A. what B. as C. that D. it

解析：