根据短文内容，完成下列句子。
No air means death. Although we can't see it, there is air around us. So air is everything and it gives life to
every living thing. 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 which
the cars give out is full of poison (有毒物). Every day we breathe it in again and again. This makes us feel sick. Besides cars, there are many factories, too. From chimneys (烟囱) of these factories, the smoke is usually
black or grey. This kind of smoke, when mixed with the air, is dangerous to our health. It is because the smoke
contains many poisonous solids and gases. In order to keep us healthy, we have to go out to the countryside to
breathe more fresh air. We can also climb up hills to get the fresh air.
1. We can't if there is no air.
2. People will have good health only when they breathe .
3. The poisonous gas can make people .
4. The from the chimneys of the factories is usually black or grey.
5. We should often go to the to breathe more fresh air.
