the old beggar walked down the street alone.he wondered ___

题目

the old beggar walked down the street alone.he wondered ___
A.which place to live in
B.which place to live
书上的答案给的是A,可我好像记得我们学过如果动词不定式做后置定语修饰的名词是place 时,后面的介词应该略去的,为什么答案会是A呢?是答案错了,还是,

答案

假如是where to live 就不需要加in,如果是用whic place 还是需要保留用in,原句是 to live in which place