There is a “ No smoking “ sign here. You _________ smoke.

--Who’s the man over there?Is it Mr Black?----It _____be him.He’s much taller.

(2013·高考新课标全国卷Ⅱ)Since nobody gave him any help，he________have done the research on his own.

He ______ it on schedule, but somehow he fell behind.

He _______ have completed his work；otherwise, he wouldn’t be enjoying himself by the seaside.