This is the difficulty we have _____ the plan.

问题描述:

This is the difficulty we have _____ the plan.
A.to carry out B.carrying out C.carried out D.with carrying out
我觉得是A,用不定式表示将要做,为什么答案是B?

B.carrying out
we have the difficulty (in)carrying out the plan
have the difficulty (in)doing sth :在.有困难.in可省