The world is not only hungry but also thirsty for water. This may seem strange to you, since nearly 70% of the earth’s surface is covered with water. But about 97% of that is sea water or salt water. Man can only drink and use the other 3% of fresh water from rivers, lakes, underground and so on. And we can not even use all of that because some of it has been made dirty.

Earth Day is April 22. But on all other days, we must also remember how important water is. The water that we use is the most important natural resource on the earth. Today we face serious water problems. One of them is water pollution. All kinds of things from cars, factories, farms and homes make our rivers, lakes and oceans dirty. Polluted water is very bad for people to drink. And dirty water is bad for fish, too.

How do cars and factories make our water dirty? First they pollute the air. Then when it rains, the rain water makes our drinking water dirty. Dirty rain, called acid rain is also bad for plants, animals and buildings. Scientists say that in 30 years, more than half of the people in the world won’t have enough clean water. We have to learn how to stop wasting water. One of the first steps is to develop ways of reusing it. Today in most large cities, water is used only once and then sent out into a sewer system (下水道). From there it returns to the sea or goes underground.

But even though every large city reused its water, we would still not have enough. So we should make use of sea water by removing the salt in it. If we can take these steps, fresh water won’t be used up.

1.The world is thirsty for water because _______.

A. we don’t have enough fresh water      B. a lot of water goes into sewer systems

C. only 70% of the earth’s surface is water                  D. sea water is widely used rather than fresh water

2.From this passage, we know acid rain _______.

A. is only bad for living things       B. is not bad for buildings and factories

C. can be produced in factories        D. is bad for people, animals, plants and buildings

3.One difficult way we can solve the problem is to _______.

A. use the water with salt in it           B. remove the salt from sea water

C. get water from underground              D. reuse the water in cities

4.What is the best title for this passage?

A. Fresh water and sea water               B. A thirsty country

C. The importance of water  D. The world’s water problem

The world is not only hungry but also thirsty for water. This may seem strange to you, since nearly 70% of the earth’s surface is covered with water. But about 97% of that is sea water or salt water. Man can only drink and use the other 3% of fresh water from rivers, lakes, underground and so on. And we can not even use all of that because some of it has been made dirty.
Earth Day is April 22. But on all other days, we must also remember how important water is. The water that we use is the most important natural resource on the earth. Today we face serious water problems. One of them is water pollution. All kinds of things from cars, factories, farms and homes make our rivers, lakes and oceans dirty. Polluted water is very bad for people to drink. And dirty water is bad for fish, too.
How do cars and factories make our water dirty? First they pollute the air. Then when it rains, the rain water makes our drinking water dirty. Dirty rain, called acid rain is also bad for plants, animals and buildings. Scientists say that in 30 years, more than half of the people in the world won’t have enough clean water. We have to learn how to stop wasting water. One of the first steps is to develop ways of reusing it. Today in most large cities, water is used only once and then sent out into a sewer system (下水道). From there it returns to the sea or goes underground.
But even though every large city reused its water, we would still not have enough. So we should make use of sea water by removing the salt in it. If we can take these steps, fresh water won’t be used up.
【小题1】The world is thirsty for water because _______.

Napoga is a 12-year-old girl in Ghana(加纳)，Africa. It is hard for her family to get clean water. Every morning，she leaves home at half past five to get clean water for her family in a village far away. It takes her six hours to get enough clean water for daily cooking and drinking. She has no time to go to school or to play with her friends. Millions of people in the world are like Napoga. They can't get enough clean water to keep healthy.
Earth Day is April 22. But on all other days，we must also remember it. The water we use is the most important natural resource(自然资源) on the earth.
Water covers 70% of the earth's surface. But most of that is sea water. We can't use it for very many things. Fresh water covers only 1% of the earth's surface.
You probably feel lucky that your life isn't as hard as Napoga's. But that doesn't mean you don't have to worry about water. We all face serious water problems. One of them is water pollution. All kinds of things from cars，factories，farms and homes make our rivers，lakes，and oceans dirty. Polluted water is very bad for people to drink. And dirty water is bad for fish，too. Now, 34% of all kinds of fish are dying out.
How do cars and factories make our water dirty？First，they pollute the air. Then，when it rains，the rain water comes down and makes our drinking water dirty. Dirty rain，called acid rain(酸雨)，is also bad for plants，animals and buildings.
Scientists say that in 30 years，more than half of the people in the world won't have enough clean water. We have to learn how to save more water for ourselves and our children. Here is some advice for saving water：
●Turn off the water while you brush your teeth. You can save as much as 450 liters(升) each month.
●Leaky taps(漏水的龙头) waste a lot of water. Fix them right away！
●You can easily cut your 10-minute showers in half----and you'll be just as clean.
●When you wash dishes，don't let the water run.
●Only wash clothes when you have a lot to wash. If your washing machine isn't full，you're  wasting water！
【小题1】On the earth，_______.