Do you know when the Great Wall _________?
(2012·山东) Be __________ —you can't expect me to finish all this work in so little time.
(2012·江苏) —Thank God you're safe!—I stepped back, just __________ to avoid the racing car.
He hasn't slept at all for three days. __________ he is tired out.
Good technique in medicine means less pain and fewer deaths and, __________ it is our duty to masterit.
I can lend you my textbook __________ you must return it to me before class.