--Excuse me, teacher, can I ask you something about the last class? I didn’t quite understand it.
--Sure! Please feel _________to ask me anything!
| A．fine | B．free |
| C．OK | D．right |
--_________ I come back before five o’clock?
--No, you________. But you can’t be back later than seven o’clock.
| A．Need, must | B．may, mustn’t |
| C．Can, can’t | D．Must, needn’t |
---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 |