看一本語法書上介紹He has no house in which to live是對的,然介詞in放后面
He has no house which to live in卻不對,為什么不對?
答：這個問題不錯!不太好回答.光說習慣是不能服人的.
首先,我們知道,He has no house 后面跟的是一個定語.
用定語從句：
He has no house where he can live.
He has no house in which he can live.
He has no house which he can live in.
這三種說法都是正確的.
其次我們知道,英語中有疑問不定式：wh-詞+不定式,可以作賓語,相當于一個賓語從句,如：
I don't know what to do.=I don't know what I should do.我不知道該做什么.
I don't know where to live.=I don't know where I should live.我不知道該住哪里.
同時,我們也見過一種介詞+which +不定式的“特殊不定式”可以作定語,相當于一個定語從句的用法,這樣的考題也是有的：
Now I’ll present the facts ____C______.
A.on which to be based my opinion B.which to base my opinion on
C.upon which to base my opinion D.which to base my opinion upon
We need more actual facts on which to base our arguments
=We need more actual facts on which we can base our arguments
至于這個相當于一個定語從句的作后置定語的“特殊不定式”為什么可以用介詞+which +不定式,而不用which+不定式+介詞,除了習慣（我們沒有見到別人這么用過）以外,也可以去理
in which =where,in which to live =where to live,這是大家熟悉的一種疑問不定式的變體.
用了介詞+which后,大家知道之間的關系,用不定式是偷懶,從定語從句變過來的.
但用了which之后,大家一方面不能馬上知道兩者之間的關系,一方面會以為后面的應該是一個定語從句（結(jié)果不是）.至于which he can live in 這個定語從句,為什么不能簡化為whcih to live in,就說不清楚了.
只能說：因為大家都不這么說,所以不能這么說.