No air means death．Though we 1 see it, air is around us． 2 air is everywhere and it gives life to every living thing．Without it we can not live．Bad air makes people 3 ．We must have fresh 4 to keep us in good health．
In the city there are a lot of people and there are too many 5 running on the road．The gas which the car sends out(排放)is bad．Every day we breathe it in and 6 ．This makes us 7 sick．So people should 8 the door as much as they can to get fresh air．There are many factories, too．The chimneys of these factories send out dark smoke．This kind of smoke is dangerous 9 our health．So in order to(为了)keep us 10 , we have to go to the countryside to breathe more fresh air or we can go up hills to get more fresh air．