-I telephoned you yesterday afternoon,but no one answered.(15)

问题描述:

-I telephoned you yesterday afternoon,but no one answered.(15)
--Really?My mother was in then,but she____ in bed.
A.must be sleeping B.must have been sleeping C.must have slept D.should have slept

真的么?我妈妈当时在家的,但是可能她当时正在睡觉
过去进行时,must 表猜测,must 后面接原型 所以选A