by which 的用法疑惑

问题描述

The country nearby promised to offer ten dollars ________ to help those who had become homeless in the earthquake.

by which 为答案。这是一个什么从句？定从么？谢谢！！

老师答疑

陈老师：

The country nearby promised to offer ten dollars ________ to help those who had become homeless in the earthquake.

by which 为答案。这是一个什么从句？定从么？谢谢！！

(1)完整定语从句为：

The country nearby promised to offer ten dollars  with which to help those who had become homeless in the earthquake.

(2)简化后的后置定语为：

The country nearby promised to offer ten dollars  with which they will help those who had become homeless in the earthquake.

曹老师：

by which应为with which。ten dollar能干什么？这个句子问题很多。造句人的水平很有限。地震后表示愿意帮助的国家不止一个吧。改为复数较好。

with which to help叫紧缩定语从句。即定语从句压缩成了一个不定式短语。其结构是介词+which+to do. 当一个定于从句的主语在句中已经出现（通常是主句的主语）并且从句的谓语含有情态动词，谓语动作是还没有发生的事情，关系代词是从句中的介词宾语。这是就可以省去主语和情态动词，不定式的to还原，就成了不定式结构作定语了。因为它是由定语从句压缩而来，所有有的语法书称其为紧缩定语从句。或叫介词+which+不定式结构也可以。这个句子如果还原成定语从句结构则为：

The countries nearby promised to offer ten million dollars with which they will help those who had become homeless in the earthquake.