(2012安徽卷)The limits of a person’s intelligence,generally speaking, are fixed at birth, but he reaches these limits will depend on his environment.
—Why does Sara know so much about Angkor Wat? —She _______ there,or she may have read about it.
—Excuse me.Is this the right way to the Summer Palace? —Sorry, I am not sure.But it _______ be.
You _______ be tired—you’ve only been working for an hour.
The engineers must have worked out the design by the end of last week,_______?
It rained a lot during their journey,so they _______ have had a good time.