19　in which to do结构　Track19

 

“介词+关系代词”这一定语从句结构，可以简化成不定式。请比较：
a.The farmer used wood to build a house in which he could store grains.
b.The farmer used wood to build a house in which to store grains.
进一步简化为：
c.The farmer used wood to build a house to store grains in.
用这一结构时我们应注意以下几点：
1）若没有与关系代词搭配的介词，我们不能采用这一结构。
I can't think of anybody whom to invite.*
2）有介词和关系代词，不能将介词置于句末。
The farmer used wood to build a house which to store grains in .*
3） "介词+关系代词”不能用一个关系副词来替换。
The farmer used wood to build a house where to store grains.*
再看下例：
a.We moved to the country so that the kids would have a garden ______.
A. in which to play
B. to play with
C. to play in
D. to play
E. where to play
F. which to play
G. which to play in
正确答案：A，C。
b.The professor could hardly find sufficient grounds_________his arguments in favor of the new theory.
A. to be based on
B. to base on
C. which to base on
D. on which to base
正确答案：D。
思考与总结：
1）本节三种判断关系代词前面的介词的方法，以第一、第二种方法最常用。
2）如何决定用第一种方法还是用第二种方法关键要熟悉各种短语的介词搭配，这是前提。
① 如果先行词是普通的名词（如book没有什么介词与其构成固定的搭配），则一般可考虑采用第一种方法：分析与定语从句中的某个动词、形容词或名词构成固定搭配的介词。例如：
He referred me to some reference books with which I am not very familiar.
② 对于较为特殊的先行词，如上文提到的extent (to the extent)，means (by the means)，ease (with ease)，rate (at the rate)，pace (at the pace)等，则可考虑第二种方法：选择与先行词构成固定搭配的介词。
3）介词的位置。
① 与动词和形容词搭配的介词：可前置（置于关系代词前），也可后置（分别紧跟在动词或形容词后面）。但若将介词后置，即置于定语从句中，则句子显得较为松散，所以最好还是前置，使句子紧凑。
② 其他情形的介词一般都只能前置（所使用的介词要放在which，whom或whose的前面）。