Question

【题目】-- Who told you the news?
-- I don't remember clearly. It ________ Mary.
-- It Mary. She doesn't know it.
A.may have been; can't be
B.can be; mustn't be
C.must have been; can't have been
D.may have been; may not be

Answer 1

【答案】A
【解析】句意：—谁告诉你的消息？—我记不清了，可能是Mary。—不可能是Mary，她不知道这事。对过去事情的可能的猜测用may/might have+过去分词；can表猜测时用于否定句和疑问句，must表示肯定的猜测，只用于肯定句。第一空意思是可能是Mary告诉我的这个消息，指对已发生的事情的猜测，用may have been；第二空表示否定，故用can't，因此选A。