Was it because of the heavy snowstorm in Europe ________ the flight had to be put off?
Does ___ matter if he can’t finish the job on time?
Don’t leave the water ______ while you brush your teeth.
He will _______ his uncle’s business when he is mature(成熟的) enough to deal with the public relations.
-- Why do you walk so strangely? --- This is ______ I fell over myself accidently yesterday and my left leg got hurt.
----Where can I stay at noon, Sir?----It depends. You can stay ____in the classroom __in the dormitory.