21. — Did you listen to the report last Friday?
— Yes, it was about the shortage of immigrant workers. That was the first time I _________ about the subject.
A. have heard B. was hearing
C. would hear D. had heard
22. — I don’t mind telling you what happened.
— You _________. I’m not asking you for it.
A. mustn’t B. may not C. can’t D. needn’t
