1.-Who's the man over there? Is it Mr Black?
-It _____ be him. He's much taller
A can't B mustn't C should D may
2.-Long time no see!
-Oh, it __ like years since I last saw you.
A looks B seems C feels D sounds
3.-It must be John who is in the office.
-I'm sure it _____ be John. I saw him off at the railway station just twenty minutes age.
A won't B mustn't C can't D needn't
4.-Listen! Helen is singing in the next room.
-It ____ be Helen. She has gone to Beijing.
A can't B mustn't C may D should