He        to keep this book for a month.

— The window must have taken you quite a lot of time that day. — Right. They____ for weeks.

In a foreign company, if you have a good command of English, you      much more easily.

—I’m going to the United States.   —How long ______ you ______ in the United States?

I suppose that when I come back in two year’s time all these old houses will ____ down．