I haven' t seen Mary these past few days. I m afraid she ____ herself for some time.

The fact that so many people still smoke in public places____ that we may need a nationwide campaign to raise awareness of the risks of smoking.

The teacher is not easy-going,and he never ____in the pupils’ games.

-—David has gone to Australia on business.—Really? I ______ why he was absent from today’s meeting.

—What is the price of petrol these days?  —Oh，it ________ sharply since last month.