The book is optional. My professor said we.... read it if we needed extra information for the essay. However, we.... read it if we don’t want to.
A.will / cannot
B.must / ought not
C.could / do not have to
D.can / should not

Please make sure to water my plants while I am gone. If they don’t get enough water, they.... die.
A.must
B.will
C.should
D.ought to

They.... be away for the weekend, but I am not sure.
A.needn’t
B.should not
C.must
D.might

You.... leave now if you wish.
A.have to
B.must
C.may
D.would

Let’s go out for a drink. – I…. love to.
A.will
B.would
C.must
D.should

He is speaking English, but I think he.... be Vietnamese, by judging by his accent.
A.will
B.could
C.would
D.should

Listen, please. You.... talk during this exam.
A.won’t
B.mustn’t
C.wouldn’t
D.coudn't

I.... go on my own. You.... go with me.
A.will / mustn’t
B.should / would not
C.could / will not
D.can / needn’t

The police searched the region carefully.... they found nothing.
A.whereas
B.nor
C.but
D.as if

We open the window.... fresh air could blow into the room.
A.for
B.so that
C.not only
D.because