Lawrence Craven,a doctor from the USA,is the author of several published reports,one of     ________introduced the idea in 1953      aspirin could reduce the risk of heart attacks.

If Sanlu Group     melamine to the milk,the babies     too much from kidney stone.

—When did you      staying up so late?

—When I entered this school two years ago, where students have too much homework to do.

—Daniel must have lost his job in that unemployment crisis,      he?

—I don’t think so. Yesterday I saw him working together with his colleagues.

—Are you sure that you are      satisfied with this job?

—Yes.Nothing can be better.

—The exam was easy,wasn't it?

—Yes,but I don’t think     could pass it.

It was not until the entrance exams were in sight that      that I had so many books to cover and so many exercises to finish.

Tourism,    it brings in money to a country,can also result in damage to the World Heritage sites there.

The man moved forward and    looked over the edge,shrinking his shoulders.

Barack Obama’s victory is a historic victory and    that promised change and overcame centuries of prejudice.