时间用when原因why,地点where经常在;
定语从句中的关系副词有三个：when, where和why，它们在定语从句中分别作时间、地点和原因状语。when指时间， where指地点，why表原因。例如：
I still remember the day when I first came to Beijing.
我仍然记得我初次到北京的那天。
The factory where his father works is in the west of the city.
他父亲工作的那个工厂在城市的西郊。
That is the reason why I did the job.
那就是我为什么干这个活的原因。
关系副词可替换，介词加上关系代;
关系副词可以由介词加上which来替换。例如：
1)This is the house where (in which) I lived two years ago.
在这句中，where= in which
2) Do you remember the day when (on which) you joined our club?
在这句中，when= on which
3) This is the reason why (for which) he came late.
在这句中，reason= for which
关系代，关系代，that与who要除外;
挑选介词要聪明，必看动词和先行;
介词后可用关系代词，但只能用which或whom，不能用that 和who。那么，这个介词怎么选呢?其一，可以看定语从句中的谓语动词;其二，可以看先行词。例如：
1) The pain from which the poor suffered in this area has attracted the attention of the public.
本句中用from 加 which, from与定语从句中的谓语动词搭配，suffer from。
2) English is a useful tool in which I can communicate with foreign friends.
本句中用in加which, 和先行词搭配，先行词表语言，因此用in。
聪明反被聪明误，只因乱用关系副;
关系副，关系副，定缺主宾它不住;
它不住，它不住，关系代词来玩酷;
关系副词在定语从句中是做状语的，where做地点状语，when做时间状语，why做原因状语，但要特别注意，如果定语从句中所缺的不是状语，而是主语、宾语或表语，就不要用关系副词，而要用关系代词。例如：
1) I still remember the days _____ we spent together in the mountains last summer.
先看定语从句中所缺少的句子成分，spent是及物动词，缺宾语，因此不能填when, 而要用关系代词which或that。
2)This is the house ______ his grandfather once lived in.
先看定语从句中所缺少的句子成分，lived in, 明显缺宾语，in是介词，介词后应该有宾语，所以不能填where, 而要用which或that。
3)Is that the reason _______ you explained to the teacher for your being late for school?
先看定语从句中所缺少的句子成分，explain后应该跟双宾语，缺少一个宾语，因此不能用why, 而要用which或that。
