The conference has been held to discuss the effects of tourism _______ the wildlife in the area.

We raised a lot of money at the charity show.—Exactly! There is useful saying, “Many hands make light work.”

You look so worried, what’s wrong -More andmore people like me begin to worry about the ______ pollution after the haze (雾霾) appeared in Beijing and some other cities in China.

we must ___ to the public the simplefact that drug are dangerous

Please _____________ . The class is too noisy.