Question

—Someone is knocking at the door. Is it Ann?—It _____ be her. She is giving a performance at th.

—Someone is knocking at the door. Is it Ann?—It _____ be her. She is giving a performance at the theatre now. A．may B．must C．can’t D．mustn’t

Answer 1

C

may 可以，可能，表示推测与其；must必须，一定；can’t不可能，可能不；mustn’t禁止。句意：有人正在敲门。是安吗？联系下文，现在她正在剧院演出。可知前文指的是不可能是她。故选Ｃ。