It’s necessary ____ us ____ wear suitable clothes onevery occasion.

The air pollution caused the of many trees in this area. We should take care of the environment.

English has a large vocabulary, hasn’t it–Yes. _____ more words and expressions and you will find it easier to read and communicate.

Sorry, but I didn’t quite understand what you said. Would you please it— OK. It’s andy19840313@126.com.

–What’s the matter with you?–After the long walk, my legs ____ and I couldn’t go any further.