— Have you been here before?—Yes. This is the third time that I ______ to Shanghai.
I _______ have been more than six years old when the accident happened.
—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,_______?