You should really _______ smoking. It’s a terrible habit.
| A．grow up | B．pick up |
| C．give up | D．set up |
---Must I tell Mike about it?
---No, you _______. He’s already been told.
| A．mustn’t | B．can’t |
| C．needn’t | D．shouldn’t |
We brush our teeth twice a day.
| A．may | B．can | C．should | D．shouldn’t |
My mother is ill. I ______ stay at home to take care of her.
| A． can | B．may | C．have to | D．maybe |
—Is Mr. Smith over there?
—It ________ be him. He has gone to Beijing on business.
| A．can't | B．must | C．might | D．can |
After a long walk, the old man be tired now.
| A．can’t | B．must |
| C．has to | D．need |