—Who______ it be that is knocking at the door?   —It ______ be Father, but I’m not sure. 
#88027
A
can; must
B
can; may
C
must; can
D
may; must
推荐题目
The Chinese teacher looks so pale. She ___ be ill.
#88979
A
must
B
mustn’t
C
can
D
need
--- I have great difficulty figuring out the answer to this problem.    --- _____ my advice, you ____ less difficulty with such problems. 
#90184
A
If you had followed, would have had
B
If you followed, would have
C
If you had followed, would have
D
If you listen, will have
We were all surprised when he made it clear that he ___ office soon.
#89034
A
leaves
B
would leave
C
left
D
had left