—How much ____the pair of trousers ? —Sixty dollars _____enough .

My teacher promised to ______ my suggestions, so I gave him some ______ .

—You look so worried, what’s wrong?—More and more people like me become to worry about the __________ pollution  after the haze (雾霾) appeared in Beijing and some other cities in China.

 His favourite _____ is science.

That Sun Yang won two gold medals in London Olympics is ______ to people all over China.