B.Rivers are one of our most important natural resources (自然资源). Many of the world's great cities are located on rivers, and almost every country has at least one river flowing through that plays an important part in the lives of its people.

　　Since the beginning of history, people have used rivers for transportation. The longest one in the United States is the Mississippi . The lifeline of Egypt is Nile. To the people of India, the Ganges is great, but it is also important for transportation; ships can travel along it for a thousand miles. Other great rivers are the Congo in Africa and the Mekong in Southeast Asia. The greatest of all for navigation(航海), however, is the Amazon in Brazil. It is so wide and so deep that large ships can go about two thousand miles upon it.

　　Besides transportation, rivers give food to eat, water to drink, water for crops, and chances for fun and recreation for the people who live along their banks. In order to increase the supply of water for crops, engineers sometimes build a dam (大坝) across a river and let a lake form behind the dam. Then people can use the water not only to irrigate(灌溉) their fields but also to make electricity for their homes and industries. However, large cities and industries that are located upon rivers often make problems. As the cities grow in size and industries increase in number, the water in the rivers becomes polluted with chemicals and other materials. People are learning the importance, however, of doing more to keep their rivers clean if they want to enjoy the benefits(利益) of this natural resource.

　　( )61. The greatest river for navigation is ___ .

　　A. the Amazon B. the Nile C. the Mekong D. the Mississippi

　　( )62. Which of the following is WRONG according to the passage?

　　A. The Nile is in India.

　　B. Almost every country has at least one important river.

　　C. Many cities are located on rivers.

　　D. Rivers play an important part in the lives of people.

　　( )63. From a dam, people can use the water for _____ .

　　A. keeping the rivers clean B. only making electricity

　　C. washing clothes D. irrigating and making electricity

　　( )64. The water in the river is polluted because of _____ .

　　A. people's drinking water too much B. people's swimming in the river too much

　　C. chemicals and other materials D. people's building a dam across a river

　　( )65. The best title of the passage is _________.

　　A. Rivers in Cities B. The Importance of Rivers

　　C. Transportation D. Natural ResourcesCNow satellites are helping to forecast the weather. They are in space, and they can reach any part of the world. The satellites take pictures of the atmosphere(大气), because this is where the weather forms(形成). They send these pictures to the weather stations. So meteorologists(气象学家)can see the weather of any part of the world. From the pictures, the scientists can often say how the weather will change.

　　Today, nearly five hundred weather stations in sixty countries receive satellite pictures. When they receive new pictures, the meteorologists compare them with earlier ones. Perhaps they may find that the clouds have changed during the last few hours. This may mean that the weather on the ground may soon change, too. In their next weather forecast, the meteorologists can say this.

　　So the weather satellites are a great help to the meteorologists. Before satellites were invented, the scientists could forecast the weather for about 24 or 48 hours. Now they can make good forecasts for three or five days. Soon, perhaps, they may be able to forecast the weather for a week or more ahead.

　　( )66. Satellites travel _____________.

　　A. in space B. in the atmosphere

　　C. above the ground D. above space

　　( )67. Why do we use the weather satellites to take pictures of the atmosphere? Because ____.

　　A. the weather satellites can do it easily B. clouds form there

　　C. the weather forms there D. the pictures can forecast the weather

　　( )68. Meteorologists forecast the weather __________.

　　A. when they have received satellite pictures

　　B. after they have compared new satellite pictures with earlier ones

　　C. before they received satellite pictures

　　D. during they study satellite pictures

　　( )69. Maybe we'll soon be able to forecast the weather for ________.

　　A. one day B. two days

　　C. five days D. seven days or even longer

　　( )70. The main idea of this passage is that satellites are now used in _________.

　　A. taking pictures of the atmosphere B. receiving pictures of the atmosphere

　　C. doing other work in many ways D. weather forecasting