问题

Who____ it be that is knocking at the door? — It ____ be Father, but I’m not sure. [ ]
A: can; must
B: can; may
C: must; can
D: may; must
B: can; may
C: must; can
D: may; must
正确答案是:
同类题型
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Do you spend a lot of time computer—No, but I spend much time doing my homework.
The reason why I didn’t go to Shanghai was________ a new job.
Yesterday, the teacher told us that the earth________around the sun.