Mary was not in her bedroom yesterday afternoon.She ______ in her classroom.
问题描述：
Mary was not in her bedroom yesterday afternoon.She ______ in her classroom.
A:should have been B:must have been C:must be D:should be 选哪个 为什么
答
B
表示肯定的猜测为什么 有have呢， 句子不是说yesterday afternoon 了吗，为什么不选 c 呢这句用must have done,表示肯定过去的事
如果选must be，就要接目前的时间，而不是昨天下午