题干

电子手表中的电流约为1.5×106A,合____mA,合____μA.天空产生闪电时电压约为107V=____kV.
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答案(点此获取答案解析)

1.5×103,1.5,104

同类题1

阅读理解
Americans like to visit the national parks. In 1996, over 250,000,000 people visited areas which are managed by the National Park Service. Experts say that by 2012, 500,000,000 people per year  will visit the parks. As a result, people are trying to think of ways to protect the parks from the crowd.   The crowding of the parks has caused several problems. One is that there is not enough space for all of the people who want to use the parks. To deal with this problem, you may have to book your    tickets a few months ahead of time. The Park Service may also raise entrance fees (费) . 
     Another problem caused by increased park use is pollution. Some garbage and waste can be cleaned up, and  the cleanup can be paid for by increased entrance fees. To cut down on noise pollution and air pollution, the number of cars allowed in parks may be limited. If this happens, people may use buses to travel around the parks. Officials may also limit the use of jet-skis, snow-mobiles, motor-boats, and sightseeing helicopters and planes.
The parks may also be in danger because of development that is going on around them. For example, around Yellow Stone Park, many hotels, golf courses, resorts, and other tourist attractions   have been built. Some of these developments have effect on areas that are used by animals. People will have to learn to agree about ways to protect the parks. If they do not, there will soon be no reason to visit these national treasures. 

同类题3

阅读下面三篇短文,根据短文内容,从所给的A、B、C、D四个选项中选出最佳选项。

C

    I live in a town. In the past, the air wasn't fresh. There was a river. People put rubbish in it. The water went bad. The fishes in the river died. There was much rubbish in the streets which weren't wide. It smelt terrible. People lived in low old houses with trees all around and had a terrible life. The children couldn't have many chances to go out to cities, not to say, have a good education. Farmers worked only with their hands. They worked very hard all year round. They planted crops(农作物)with the help of animals. The poor people went anywhere on foot, and only some rode bikes. Few visitors came here to spend their holidays.

    At present, things have been greatly changed. People have moved into big bright houses or beautiful buildings. There is a big factory. Many people work in it. They are getting richer. Different kinds of cars and buses are running in the big streets. It is faster and easier to travel. People plant many fruit trees and get much money. People plant crops with the help of machines which can save lots of work. Students can study in a modem school. People pay more attention to the environmental protection. The mountains are becoming greener, water much cleaner. What around us is the clearer sky and greener water. As a result, many visitors come here to spend their holidays. People enjoy their modern life. But with the development of the industry, we have fewer trees. Air and water pollution is becoming more and more serious. We must do something to stop pollution to make our town more and more beautiful.