根据句意、首字母或中文提示写出单词。
【小题1】Firing the crop stalks（秸秆）leads to __________（严重的）air pollution.
【小题2】It’s __________（明智的）for you to ride a bicycle to go shopping in Beijing.
【小题3】People in the world should protect the environment by __________（循环使用）.
【小题4】Please  t_________ off the lights when you leave your bedroom.
【小题5】It’s all our duty to __________（减少）air pollution.