— Oh,why is your room so dirty?I wonder ______ .
— Yes.I cleaned it half an hour ago.Maybe the cat came here just now.
A.if you have cleaned it B.that you cleaned it C.did you clean it
Look!The woman atthat table ______ be our teacher.She often sits there.
— No,it ______ be her.She has gone to Chengdu for a meeting.
A.must; can’t B.must; mustn’t C.can; can’t