23'

Without air nothing can live.Although we cannot see it, there is air around us.So air is everywhere and it gives life to every living thing. Without it all living things will die.

75'

Bad air makes people ill.We must have fresh air to keep us in good health.In the city, there are a great many people and there are too many cars running on the roads.The gas that the cars give out is full of dirty things.Every day we breathe in the waste gas again and again.This make us become ill.So people should go outdoors as much as they can.
1. make sb.ill 使某人生病
2. have fresh air呼吸新鲜的空气
3. keep sb. in good health使某人保持健康状态
4. give out发出
5. breathe in吸入
6. the waste gas废气
7. go outdoors到户外去
8. as much as they can尽可能多地

194'

Besides so many cars, there are many factories, too.From the chimneys of these factories, we can see the smoke is usually black or grey in color.This kind of smoke is dangerous to our health.This is because there are many small harmful things and gas in the smoke.So, if we want to keep healthy, we must go out to the country to breathe in more fresh air.We can also go up hills to get more fresh air.
1. besides包括...在内
2. be dangerous to对…有害的
3. harmful things有害的物质
4. keep/stay healthy保持健康

138'

This passage says that more and more waste gas from the___1__in the city, plus the___2___from factory chimneys have made the air very__3__.It is also tells us that we should do more exercise and enjoy more ____4___air if we want to stay __5____.

171'