----Will you take up teaching as a career after graduation?---- Hard to say. I ________ go abroad for higher education instead, but it depends. 

—Have you seen Maragaret? The boss is looking for her everywhere.—She________the train, otherwise she would have arrived here by now.

——Will you stay for lunch?——Sorry，       . My brother is coming to see me.

—He should have come to join in the thorough cleaning.—He _____. I don’t think it was his turn.

If you _____ smoke, please go outside because this is a non-smoking office.