She had a little fortune in the bank _______ which to help her mother．

A.in

B.of

C.with

D.for

答案及解析： C

解析：

本题考查“介词+引导词”。当主句的主语和定语从句的主语相同时，可以把定语从句简化成引导词加不定式to的形式。这道题变成正常的定语从句为：She had a little fortune in the bank _{___} which she could help her mother．显然，which的先行词是fortune，根据搭配原则，应说do sth．with fortune/money…，因此，这里的介词应用with，即C项。