where作定语从句：
关系副词when、where、when引导定语从句的具体用法
① 先行词表示时间、地点、原因时，在定语从句中作状语，选择相应的关系副词when、where、why引导定语从句。若其在定语从句中作主语或宾语，则选择关系代词引导定语从句。区别三组例句：
where he lives.
a. This is the place
that/which he visited last year.
when my brother was a little boy.
b. I still remember the time
that/which we spent together.
why he was late.
c. This is the reason
that/which he gave us.
②某些非地点时间名词有定语从句修饰，关系词在从句中作状语，由where引导定语从句（stage, case, point, situation）；同样用法的'还有occasion,由when引导定语从句。
e.g. I can think of many cases where students know a lot of words but don’t write a good essay.
There are many occasions when people don’t know what they want.
定语从句还是状语从句的区别
一、where引导定语从句时, where是关系副词, 在从句中作地点状语, 其前面有表示地点的先行词, where引导的从句修饰先行词。例如:
The bookshop where I bought this book is not far from here.
This is the house where I lived two years ago.
We will start at the point where we left off.
二、where引导状语从句时, where是从属连词, where引导的从句修饰主句的谓语动词, where前面没有表示地点的先行词。例如:
Wuhan lies where the Changjiang River and the Han Jiang River meet.
Make a mark where you have any doubts or questions.
I found my books where I had left them.
有时, where引导的地点状语从句兼有抽象条件含义, 可放在主句的前面, 而where引导的定语从句则不能。例如:
Where there is a will, there is a way. 〔谚语〕有志者事竟成。
Where there is water, there is life. 有水的地方就有生命。
三、在有些情况下, where引导的定语从句可转换为where引导的地点状语从句。例如:
A tall building was put up at the place where there used to be a desert. （＝A tall building was put up where there used to be a desert. ）在以前曾是沙漠的地方盖起了一幢高楼。
Bam boo grows best in places where it is warm and where it rains often. （＝Bamboo grows best where it is warm and where it rains often. ）温暖而多雨的地方最适合于竹子生长。
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