.—Who______ it be that is knocking at the door? —It ______ be Father, but I’m not sure.
—________ is the richest man in this town? —I think Mr Kim is the richest man.
Many sailors think that a thick fog is their ________ enemy.
I made a suggestion ________ he ________ to Australia for further education.
—Will you ________ our house while we are out on holiday? —Well, that ought to be no problem.
The chairman thought _____ necessary to invite Professor Smith to speak at the meeting.