根据短文内容及所给首字母提示写出所缺单词， 并将完整单词填在下面对应题号后的横线上。

     Air is very important to everything that lives. But the air we breathe is (1)g______ dirty. People all over

the world are looking for (2)w______ to make it clean again.

     Have you (3)e______ watched the smoke from chimneys (烟囱) rising high in the air? Have you

(4)s______ the smoke from cars and trucks on roads or the smoke from planes? The smoke is not

(5)g______ to breathe. If we want to keep healthy and strong, we need to breathe (6)c______ air.

     (7)W______ more and more factories everywhere and more and more cars, trucks and planes, it is

getting harder and harder to do with the air (8)p______.

     Scientists have (9)a______ taken actions to stop or slow down some of the things that make the air dirty.

They will not stop working (10)u______ we have clean air again.