When it ________ air pollution, Beijing faces the three “C”s, cars, coals and construction, which lead to Beijing’s thick air pollution.
The dictionary doesn't belong to your brother ____ _____ , but it belongs to me.
__ we know, in a chemical change, energy cannot be created, ____.
People ___ her because she ___ such a strange hat.
In such weather.Tom prefers ____ at home ____ go out for playing.