My sister will never speak to others like that ________they say something unpleasant to her .

Barack Obama delivered a speech to 500 local youths during his visit to China, many of _______ were from Fudan University and Tongji University.

So quickly are science and technology advancing ________ is a possibility today may be a reality tomorrow.

I remember_____the factory owed a small workshop and two machines.

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.