Trees ____ fight air pollution．They are natural air conditioners．
#78302
A
should
B
must
C
need
D
can
推荐题目
The motorbike _____ start, no matter how hard he tried.
#62786
A
shouldn’t
B
couldn’t
C
wouldn’t
D
mightn’t
—I think the man over there must be Bob. -- It_______ be him. He has______ to Australia.
#78073
A
can’t, gone
B
can’t, been
C
may not, been
D
mustn’t, gone
______ I have a quick word with you? Something important has happened.
#62748
A
Must
B
Could
C
Would
D
Should
One of our rules is that every student ______wear school uniform while at school.
#62828
A
might
B
could
C
shall
D
will
We have bought so much food now that Tom won’t be with us for dinner.
#63146
A
may not
B
needn’t
C
can’t
D
mustn’t