—Sorry, sir. I can’t answer this question. ---Well, you are supposed______ this part of history.

Teachers recommend parents________ their children under 12 to ride bicycles to school for safety.

I must go there earlier. John has suggested that I _____an hour before the discussion begins.

(2013·浙江，8)Eye doctors recommend that a child's first eye exam ________ at the age of six months old.

The professor gave orders that the test ____before 5:30.