⒈特殊疑问词"where/when/why/how"也可以引导定语从句。
与关系代词引导定语从句不同，特殊疑问词引导定语从句时在从句中做状语，所以特殊疑问词也叫关系副词。
This is the city where I met Mary.
He came on Friday,when it was raining very hard.
I don't know the reason why he cried.
That's how/the way he handle the thing.
⒉关系副词的功能:
where 用来修饰表示地方的名词
when 用来修饰表示时间的名词
why 用来修饰 the reason
how 和 the way 只能用其一，表示方式。
⒊where 举例
This is the place where I lost my key.
I met him at the station ,where there were many passengers.
I bought a desk where I could put my books on.
⒋ when 举例
That's the year when he graduated.
The son rose at 5:30 ,when most people were still in their dreams.
⒌ why 举例
I don't know the reason why he cried.
That's the reason why she was late.
⒍ how 举例
how 只修饰 the way，且只能出现其一
That's how he handle the problem
=That's the way he handle the problem.
I am sick of the way he looks at me.
⒎关系副词的使用要点
a. 在限定性定语从句中，where不可省略，when 和 why 可以省略，how必须省略:
That's the place he was born ()
That's the place where he was born.()
I shall never forget the day (when)
he came () That's the reason (why) he left.()
I am sick of the way how he looks at me.()
I am sick of the way he looks at me.()
b. 当先行词做表语时，可省略先行词
That's the place where he was born
=That's where he was born
That's the day when he'll come
=That's when he'll come
That's the reason why he left
=That's why he left
That's the way he did it
=That's how he did it