How long do you think it will be _______ scientists succeed in providing a cure for cancer?

A. when       B. after       C. since      D. before

How long do you think ____ the car factory launches a new model?

A. will it be until B. will it be when     C. it will be before        D. it will be that

How long do you believe it will be _____ Chinese people land on the moon?

      A．before   B．since      C．when      D．that

“How long do you suppose it is _______ he left for Japan?” “No more than half a month.”

A. when  B. before  C. after D. since

---How long do you think the terrible snow will _____?

--Sorry, I didn’t listen to the weather forecast.