As more and more cars are produced and used, so the _____ from their exhaust-pipes contains an even larger volume of poisonous gas.
There isn't an empty table. Would you mind_____? ( )
Once you want to do something, you must get down _____it well. ( )
It was yesterday _____I went to the railway station to meet my uncle. ( )
Liu Yang became the first woman astronaut in China _____into space. ( )
-What's the matter? -The cook _____five minutes ago, and there are fifty dinners still to cook.( )