---Must we donate our pocket money to the poor right now?---No, you _______. You can think it over and do it before Friday.

---Could I use your bike? ---Yes, of course you_________.

—Look at the picture on the wall. It ________be David’s.—Yes, his name is on the first page.

.--- Where is your father? --- I'm not sure. He_______ in the office.

  —The winner is a tall and thin boy with glasses!—Well，it________ be Mike.  He doesn’t wear any glasses.