______Yang Liwei succeeded in circling the earth ______ all Chinese people.

There is thick haze(雾霾)around many cities in China recently. What do you think of it —I think __________ cars we drive, the less pollution the city has.

I don’t think a warm winter always has a negative influence on our life, _______?

Several companies are__________ each other__________ a contract（合约）.[ ]

Could you please come to the museum with me this afternoon—Sorry, I ______ . I have to take a piano lesson at 2 pm.