If you try to sit on two chairs,you will fall them For life,you must choose one chair. A between B under C among D into
______ great scientist Qian Xuesen is!
I don’t know when he ______. When he ______, I will let you know.
------Whose shirt is this? ------ It _______ be Li Lei’s. It is too big for him.
Stop smoking, _______ you will get better soon.
—How long have you _______________ the motorbike? —For about two weeks.