问题

They had much difficulty ____________ the problem and they needed our help.

A:working out
B:work out
C:worked out
D:to work out;

正确答案是：

同类题型

What do you think of this book—–I am _____ in this _____ story book.

I met Kate on ___________way homeyesterday.

He is a man who lacks experience and determination, and I think he is not ________ the job.

It usually takes about ten minutes ____to school.

He is on diet(节食) because he wants to be _____.