We had a very difficult time ______ some of the problems 选项:a、discussing b、to discuss c、to kn

问题描述:

We had a very difficult time ______ some of the problems 选项:a、discussing b、to discuss c、to kn

a

b

have+ 宾语+宾语补足语
have a very difficult time (in)doing sth
所以用discussing 表示已发生的情况.