___ the fact that he found math boring, he was still good at it.
—Bob has gone to California. —Oh, can you tell me when he ______?
Leave your key with a neighbor _____you lock yourself out one day.
It was two weeks before the Spring Festival and the shopping centre was _____ with shoppers.
Many students go to school _______ the tube in Beijing every day.
Stop making noise, _______ the neighbors will start complaining.