Great changes _________ in Tongren in the past five years.
| A．have happened | B．have taken place |
| C．have been happened | D．have been taken place |
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 |
You ________ worry about him. He will get well soon.
A. needn’t B. can’t C. mustn’t