— Come and join us, Ben!

— I’m afraid I can’t. I’m too busy now. If I ________ time, I would certainly go.

A. had                                   B. will have                           C. have had                 D. have

— Mum, I’m too tired to walk any farther.

— You mean it’s _________ to take a taxi?

A. popular B. necessary C. possible D. interesting

—Excuse me, could you help me take this chair to my office?
—I’m sorry, ______ I can’t help you right now. I’m too busy.