大学英语：定语从句中的介词+关系代词结构

英语正式的文体，尤其是法律和科技文献中，定语从句中的关系代词（主要是which）前往往加介词，介词的选择有时取决于从句中的动词结构，有时又取决于主句中关系词前面的名词结构。因此介词的选择既要注意其后的也要注意其前的搭配关系。

Physics,about which I know nothing,doesn’t seem so dull a subject.(定语从句可以转换成I know nothing about physics,可以看出 about 与 know 有关。)

This depends on the purpose for which the examination is given.(定语从句可以转换成the examination is given for ... purpose，介词for与purpose有关。)

注意：在语义上相当于一个简单动词的短语动词中的介词不能前置，只能用在动词后。

This is a phase of history which it is sad to look back on.

The baby whom she is taking care of is very lovely indeed.

口语中要避免这种结构，关系代词which往往省略。

There’s a limit (which) nobody should go beyond.

That’s something (which) they can never put up with.