Question

she must have been in her classroom

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

Answer 1

b。
mary昨天下午不在卧室，她肯定是在教室。
首先，根据时间排除掉c和d.然后a选项表示的是“她应该在教室，（结果没有在，）表示责怪的意思，”不符合题意，所以选b.