阅读理解。 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 spread out is full of poison. Every day we breathe it in again and again. This makes us feel sick. Besides so many cars, there are many factories too. From the chimneys of these factories, we get the smoke usually in black and grey colour. This kind of smoke, when it mixes the air, is dangerous to our health. It is because smoke contains many poisonous solids and gases. So in order to keep us healthy we have to go out to the countryside to breathe more fresh air. Or we can go up hills to get more fresh air. 1. Which of the following best explains that no air means death? [     ] A. Air gives life to every living thing B. Air can't be seen anywhere around us C. Bad air makes people sick D. Fresh air keeps people healthy 2. According to the passage, we know that . [     ] A. going up hills is very good to our health B. smoke from chimneys is more serious than gas from cars C. We shouldn't go out of doors as much as possible D. A great many people have to breathe air again and again 3. The best title for the passage is . [     ] A. Fresh Air B. The Use Of Air C. Breathing Air D. Bad Air