– Excuse me, sir. But nobody _____ smoke here in the lift! -- Sorry! I didn’t see the sign. 

Sometimes smiles ______ be false, hiding other feelings like anger, fear or worry.

I am fond of my sister but she has one serious shortcoming. She _________ be really stubborn.

— What are you going to do this weekend?— I don’t know. I ______ visit a friend.

---I can’t stop playing computer games. --For your eyes,my boy,I’m afraid you______.