I单项选择（共15小题；每题1分，满分15分）
21. -----What about having a rest?
----- __________________
A. Good idea B. Help yourself C. Go ahead D. Me, too.
22. – You are always thinking of yourself! You kept me waiting for two hours.
-- I am sorry that you _____think so.
A. would B. can’t C. should D. needn’t
