3. why指原因，在定语从句中做原因状语
eg. Please tell me the reason why you are
late.
注意：关系副词引导的从句可以由“介词+关系代词”引导的从句替换
(1) The reason why/ for which he refused the
invitation is not clear,
(2) From the year when/in which he was going
to school he began to know what he wanted when he grew up.
(3) Great changes have taken place in the city
in which./where I was born.
判断关系代词与关系副词：
方法一： 用关系代词，还是关系副词完全取决于从句中的谓语动词。不及物动词后面无宾语，就必须要求用关系副词或者是介词加关系代词；而及物动词后接宾语，则要求用关系代词。例如：
This is the mountain village where I stayed
last year.
I'll never forget the days when I worked
together with you.
(错) This is the mountain village where I visited
last year.
(错) I will never forget the days when I spent in
the countryside.
(对) This is the mountain village (which) I
visited last year.
(对) I'll never forget the days (which) I spent in
the countryside.
习惯上总把表地点或时间的名词与关系副词 where, when联系在一起。此两题错在关系词的误用上。
方法二： 准确判断先行词在定语从句中的成分(主、谓、宾、定、状)，也能正确选择出关系代词/关系副词。
例1. Is this
museum ___ you visited a few days ago?
A. where B. that C. on which
例2. Is this the museum ____ the exhibition was
held?
A. where B. that C. on which
关系词的选择依据在从句中所做的成分，先行词在从句中做主、定、宾语时，选择关系代词 (who, whom, that, which, whose)；
先行词在从句中做状语时，应选择关系副词 ( where 地点状语，when 时间状语，why 原因状语) 。
Exercises:
- The
man ____ is standing there is my father.
A. who B. whom C.
which