It was not until the subprime loan crisis(次贷危机) ____ great damage to the American financial system that Americans ____ the severity of the situation.
—She looks very happy. She ________ have passed the exam.—I guess so. It's not difficult after all.
A survey has shown that 40% of those killed in traffic accidents ________ if they had been wearing seat belts.
—The research on the new flu virus vaccine is challenging and demanding.Who do you think can do the job?—________ my students have a try?
—Mum, can I watch the TV program for another twenty minutes?—Sorry, dear, it's time you ________ to bed.
________ him not to do so, he wouldn't have made such a serious mistake.