1．—You didn't wait for Mr.Black last night, did you?
—No, but we ________.He didn't return home at all.
A．couldn't have B．needn't have
C．didn't need to D．should wait have
2．Tom hasn't come to work since last Friday.________ he have had an accident？
A．Must B．Should C．May D．Can
【答案】D 【解析】疑问句的推测常可用can，一般不用must / may。
3.—How did you do in the test?
—Not so well.I ________ much better but I misread the directions for writing.
A．will have done B．could have done
C．must have done D．may have done
【答案】B 【解析】but所表达的是一种含蓄条件，由其后的过去时态可知此处该用“could＋完成时”的虚拟形式。
