Nobody knows for sure how dinosaurs died out 65,000,000 years ago. It _______ because of sudden changes of their living conditions.
#62591
A
must have happened
B
would have happened
C
should have happened
D
might have happened
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--- Shall I tell John about it? --- No, you _____. I’ve told him already.
#63475
A
mustn’t
B
wouldn’t
C
shouldn’t
D
don’t have to
I was really anxious about you. You____ home without a word.
#62986
A
mustn’t leave
B
shouldn’t have left
C
couldn’t have left
D
needn’t leave
You ________ play with the knife. You ________hurt yourself.
#75972
A
mustn’t; may
B
mustn’t; must
C
shouldn’t; must
D
can’t; should
One of our rules is that every student ______wear school uniform while at school.
#62828
A
might
B
could
C
shall
D
will
— May I smoke here?— No, you ______ . This is a no-smoking room.
#75754
A
needn’t
B
mustn’t
C
couldn’t
D
wouldn’t