雅思写作之重难点（2）
一、as,which
的非性定语从句的区别。
1. as 和which引导非性定语从句的区别 As we all know, his parents were killed in the war.
a. as代表前面主句意思时，有“正如…”之意，而which没有此意思，从句中的动词常是expect, know, see, think, want, suppose等。 He won the match, as we had expected. He agreed to the plan, as was to be expected. The police were looking for him, as he thought.
b. which 引导的非性定从只能位于主句后，as引导的非性定从可以位于主句之前、之后或之中。 As is expected, the result is satisfactory. = The result, as is expected, is satisfactory. = The result is satisfactory, as is expected
c. 在as + is/ was + 过去分词结构中 is/ was 可以省略，而在which引导的该结构中，is或was不可省略。
Lincoln was shot in a theatre, as (was) described in the film.
2. 介词加关系代词
1.根据从句中动词与先行词的逻辑关系，请体会： e.g. Is that the newspaper for which you often write articles? 2. 根据从句中动词或形容词的习惯搭配，如：
e.g. Can you explain to me how to use these idioms about which I’m sure.
3. 根据先行词与介词的搭配习惯，请体会： e.g. 1949 was the year in which the P.R.C. was founded.
注意： 如果关系从句中的动词是由两个单词组成的短语动作（例如come across， fill in， look after， take on ）
The Roman coins which a local farmer came across in a field are now on display in the national museum.
二、定语从句的特殊用法。
1.先行词在定从中所在的是一个整体性词组提前引导。
使用情况：两句子中的相同名词（先行词）在定从中翻译过来时在一个词组中，这时要将该词组整个提前来引导定从。此类定从也需要用逗号与主句隔开。
整理性的词组=“表示一个包含先行词在内的更具体的地点” “表示先行词的一部分”（all, both,
each,many,most,neither , none, some, the majority, part,… 数字 one, two, 分数，最高级，the best, the biggest….. of+which/whom /whose+n ） 举例：
1．书桌上有个杯子。There is a cup on the table.
在杯子的顶端，有一只苍蝇。On the top of the cup, there is a fly. 例句中的两句话合成定从：On the table there is a cup, on the top of which there is a fly.
我看了一群人。I saw a group of people.
人群中的大部分人是中学生。The majority of the group are middle school students.
I saw a group of people, the majority of which are middle school students.
3. 我有一本书。I have a book.
书的很多文字和插图都很有意思。Many words and illustrations of the book are fun.
I have a book, many words and illustrations of which are fun.
必须搞清楚which, who或whom引导的是定语从句，而以and连接的是并列句。
• He has a lot of magazines, some of which are about sport. = He has a lot of magazines ，and_______________ are about sport.
• There are fifty students in the class, three-fifths of whom are girls. • There are fifty students in the class ,and ___________ are girls.
2. that 引导定语从句，名词性从句和强调句的区别
关系词常有3个作用： ①连接作用，引导定语从句。 ②代替先行词。
③在定语从句中担当一个成分。
That 引导名词性从句和强调句都不做成分，只起到连接作用 It was the company that he loved for ten years. It was in the company that he worked for ten years. 判断依据：去掉”It is…that”句子结构是否完整。
8. 用于the same…as…,such…as…，as…as…, so…as…中，一般用as。 e.g. Such books as you tell me are interesting. This is the same book as I lent you yesterday. Here is so big a stone as no man can lift.
定语从句such/ so… as 与状语从句such/ so… that的区别 Here is so heavy a case as no one can move. Here is so heavy a case that no one can move it.
as引导的是定语从句，as 在从句中充当主语，宾语或表语；that 引导的是状语从句，that 在从句中不充当任何成分，其后一定是一句完整的句子。
