、Tom is a top student in our class , How        it be that he was a failure in the last exam?

Teachers        be sensitive to the development level of each student so as to help them better.

-- What’s wrong with your pen?
-- The ink ___________ come out.

— May I smoke here?
— No, you ________. Can’t you read the sign “NO SMOKING”?

—“Crash diets” make us lose weight fast and I am all into that.
—But it_______better to work out.　   

— Is Jack on duty today?
— It ________ be him. It's his turn tomorrow.

－Are you coming to the English evening?
－I’m not sure. I     go to the concert instead.

You _____ her in her office last Friday, she’s been out of town for two weeks.

--- Guess what! I have got A for my term paper.
--- Great! You _____ read widely and put a lot of work into it..

This basketball team had lots of excellent players, so its fans never expected that it ____ have failed in the final.