21. The United Nations set _______ deadline for that country to accept _______ peace plan.

A. the; the         B. the; a             C. a; the             D. a; a

22. — Hey, you haven’t been acting like yourself. Everything OK?

—_______.

A. Sure, it is        B. I’m fine, thanks      C. That’s good       D. It’s a pleasure

23. — Has Yang Liping returned from Yunnan yet? I’d like to meet her.

   — Sorry. She _______ back here only for last weekend.

A. has been        B. would be            C. had been                 D. was