怎么理解有时候要介词,有时候不用1.Ineedapentowritewith.为什么write后有with2.heislookingforaboxinwhichhecanputtheapples.heislookingforaboxtoputtheapplesin.前面那句没有in后面那句有in?

Question

怎么理解有时候要介词,有时候不用
1.I need a pen to write with.为什么write后有with
2.he is looking for a box in which he can put the apples.
he is looking for a box to put the apples in .
前面那句没有in 后面那句有in?

Answer 1

1.考察不定式做后置定语,从逻辑意义来说,write 和 pen没有动宾关系,所以我们只能说write with a pen,而不能说write a pen.再例如：I need a room to live in.
2.第一句话是介词+关系代词引导定语从句,介词的位置可以在关系代词之前,也可以在定语从句之后,只是习惯上放前.
第二句话和第一题差不多,我们只能说 put the apples in a box,而不能说put the apples a box.