--“Where is Tom?”--“He hasn’t come to school today, I think he ______be ill.”

Generally my father is a mild man, but when he gets angry, he ______ be fierce.

—I’m afraid you missed a fantastic lecture yesterday. How come you were absent from it?—If you _______ know, I asked for a day off and visited a relative of mine in hospital.

 The boss has given everyone a special holiday, so they      go to work tomorrow .

What do you mean, there are only ten tickets? There _________ be twelve.