How long do you think it will be______man can finally solve the problem of cancer?—Well，it depends

Who has found out the answer _____ this question?

Our house is on the top of the hill, and in winter the winds ______ be pretty cold .

sigh over the small achievement. _____, and I’m sure if you keep at it, you’ll see the light at the end of the tunnel!

Xi’an is really a fascinating city andwe’ve decided to stay for two weeks.