问题补充:
---There is somebody knocking at the door. Who it be?
---I’m not sure. It be a postman.
A. may; must
B. will; can
C. can; may
D. may; will
答案:
A. may; must
B. will; can
(答案→)C. can; may
D. may; will
解析:may可以,可能;must必须,一定;will将要;can能,可能。句意:有人在敲门。可能是谁?——我不确定。可能是邮递员。结合语境可知选C。