One ought ________ for what one hasn’t done.

o you think of his talk on InformationTechnology —Oh, excellent It’s worth ________

What a heavy rain!— So it is. I prefer rather than on such a rainy day.

－So many problems! I’m too tired.－You should try to _________ them by yourself. You’re not a child any longer.

The telephone system _________ during the big earthquake in Sichuan Province.