1 . —I heard our boss suffered great loss because someone had leaked information to our competitor.
—___________ that betrayed us? He was the first to be fired.

A．Must it be Sam	B．Can he be Sam
C．Can it have been Sam	D．Could he have been Sam

2 . Not all flowers have a strong fragrance. Some ___________ be smelly. Those that sell well ___________ be the beautiful and fragrant ones.

A．may; must

B．must; may

C．can; should

D．should; can

3 . Old age _______ burn and rage at the close of day; rage, rage against the dying of the light.

A．couldn’t

B．should

C．wouldn’t

D．shall

4 . —He ______be in the classroom. I think.
—No, he ______ be in the classroom. I saw him go home a minute ago.

A．can; may not

B．must; may not

C．may; can’t

D．may; mustn’t

5 . If someone happens to have high fever and pneumonia, he or she _________ seek treatment fast.

A．must

B．needs

C．may

D．could

6 . With no gravity to push against, astronauts’ bones and muscles ________become weak.

A．should

B．must

C．can

D．need

8 . —Everyone in my class passed the exam.
—Oh, really? It ________ difficult.

A．can’t have been	B．needn’t have been
C．must be	D．mightn’t be

9 . —Where ________ little Tom be now?
—I wonder what he ________.

A．can;is up to	B．must;is about
C．may;is doing	D．must;playing

10 . The world went into shock, most people having assumed that this space flight ________ be more dangerous than travelling in an aeroplane.

A．should

B．shall

C．would

D．could