英语句子语法问题thetableillutratesthechangesintheextenttowhichresidentsofacityweresatisfiedwiththeirlives.为什么which前有个to,什么用法?把to去掉不行吗?经常看到从句前有个介词出现,比如ofwhich,t

Question

英语句子语法问题
the table illutrates the changes in the extent to which residents of a city were satisfied with their lives.
为什么which 前有个to,什么用法?把to去掉不行吗?
经常看到从句前有个介词出现,比如 of which,to which,in which,in where等等.怎么判断和如何使用是否在引导词前加介词?
还有一个例子
the figures for other aspexts of life saw a decline in 2010,by which time public transport had become the main problem.
出现了by

Answer 1

定语从句加在关系词加介词通常要看固定词组和表达的意思,加这个介词的方法组要有：
1,介词与先行词组成词组,如句1中的 to which,which指代extent 程度,to some extent/degree 是词组
同样的,句二中的by which 也是同样的原则,which 指代 2010 ,by which ：到.为止；
2,介词与定语从句中的谓语动词组词搭配或者词组；常见的有,
He is the man ,to whom we usually turn for help；中to whom 中的 to 与从句的turn组成搭配；
相对而言,第一种比较灵活,第二种相对简单一些,只要平时多留意,应该不是很难.