问题
选择题
Their answers are exactly the same. One of them ___ from the other.
A．must copy
B．must have copied
C．should copy
D．should have copied
答案
答案：B
题目分析：句意：他们的答案一模一样，一个人一定是抄袭另外一个人的。根据句意是对过去的情况的肯定推测，首先排除AC，因为它们是表示现在情况，must have done过去一定做了，should have done过去本应该做而没做，选B。