21£®--Shall we go and visit Mr. Wang tomorrow?

   --____________.

A. It depends       B. That depends on      C. It is depended         D. That depends so

22. No sooner _______home than the telephone rang.
A. he had arrived         B. had he arrived                C. he arrived        D. did he arrive

23. I will never go to his house unless_______.
A. I invite           B.I will be invited        C. invited             D. I was invited

24 __________ all day at home writing, the novelist went out for a walk in the evening.

A. Spent              B. Spending                C. Having spent          D. Having been spent