He is fluent in English because he once stayed in London ． —- Really ? How long _________ there ?

I wonder when they ___ for Beijing. I will go to the train station to see them off whenthey ______.

It will be hard for us to get up in the morning if we________ to bed too late.

I ______ the film if I’m free next Sunday.

Trees can prevent the wind _____ the earth away.