—Who______ it be that is knocking at the door?—It ______ be Father, but I’m not sure.A. can; must B. can; may . must; can D. may; must
A person___e-mail account is full won’t be able to send or receive any e-mails
Samuel can’t help having a big nose---it is___of him to be curious about other’s affairs
These product are very cheap because the industry___the raw materials,the prices of which remain low
—How long are you staying? —I don’t know.___
Having been ill in the bed for nearly a month,he had a hard time___the exam