问题补充:
.--- Where is your father?
--- Im not sure. He in the office.
A. must be
B. maybe
C. may be
D. perhaps
答案:
A. must be
B. maybe
(答案→)C. may be
D. perhaps
解析:句意:---你父亲在哪里?---我不确定。他可能在办公室。must be一定是,表示对现在事实的推测;maybe副词,可能,大概,也许;may be可能是,表示对现在的可能性推测;perhaps副词,可能,大概,也许。因为空后无任何系动词或实义动词,故需填情态动词+be结构,有因为题干中有Im not sure表示不确定的成分,故选C。