问题 解答题
下表是太阳系八大行星与太阳的距离.改写成以“万”为单位的数.
行星距离(千米)距离(万千米)
水星58050000
金星108450000
地球150000000
火星228600000
木星780750000
土星1436400000
天王星2892000000
海王星4519500000
(1)哪个行星离太阳最近?是多少?
(2)哪个行星离太阳最远?是多少?
(3)海王星与太阳的距离是多少千米?其中两个5表示的意义相同吗?分别表示什么?
答案

下表是太阳系八大行星与太阳的距离.改写成以“万”为单位的数.

行星距离(千米)距离(万千米)
水星580500005805万
金星10845000010845万
地球15000000015000万
火星22860000022860万
木星78075000078075万
土星1436400000143640万
天王星2892000000289200万
海王星4519500000451950万
答:(1)水星行星离太阳最近,是5805万千米.

(2)海王星行星离太阳最远,是451950万千米.

(3)海王星与太阳的距离是451950万千米,其中两个5表示的意义不相同,左起第一个5在亿位上表示5个亿、第二5在十万上表示5个十万.

单项选择题
阅读理解

Scientists have developed a water treatment system that they say is a powerful but simple way to save lives. Four grams of chemicals can treat ten liters of dirty water for a low cost, about ten cents.

Experts say infections from dirty water kill several thousand children in developing countries every day. The Procter and Gamble company has been developing the "PUR Purifier of Water" system since 1995. The company has been working with the United States Centers for Disease control and Prevention(C.D.C.).

C.D.C. researchers tested it in Guatemala, Pakistan and Kenya. Procter and Gamble researcher Greg Allgood says cases of diarrhea(腹泻) in those studies fell by about 50 percent. Researchers from Johns Hopkins University in Maryland tested the system at a refugee camp in Liberia. Mr. Allgood says that study found a reduction of more than 90 percent. Use of the system is being expanded worldwide.

The treatment contains bleach(漂白剂) to kill disease-causing organisms. It also contains something that dirt and other particles stick to. Mr. Allgood says the chemicals can remove lead and other dangerous metals and even agricultural poisons like D.D.T.

Mr. Allgood heads the Children's Safe Drinking Water program at Procter and Gamble. He says about forty million packets of the treatment have been given to countries for free. They have been used in emergencies and in areas with limited supplies of clean water.

Clean water is a limited resource in many parts of the world. Delegates from about 130 nations attended the Fourth World Water Forum last month in Mexico City. Scientists, policy experts and others discussed ways to provide clean water to the world’s poor. Organizers say more than twenty percent of the world population lacks clean drinking water. The final declaration did not go so far as to declare water a human right. But it did say that governments, not private companies, must take the lead in improving the public’s ability to have clean water.

46. What is mainly talked about in this passage?

A. Water pollution around the world.

B. The causes of diarrhea in African countries.

C. A newly developed water treatment system.

D. The Fourth World Water Forum in Mexico City.

47. Which of the following developed the water treatment system?

A. The US Centers for Disease Control and Prevention.

B. The Procter and Gamble Company and C.D.C.

C. The Children’s Safe Drinking Water Program.

D. Johns Hopkins University.

48. Which of the following about the new water treatment system is NOT true?

A. It is effective but very expensive.

B. It was tested in Guatemala, Pakistan and Kenya.

C. It is being expanded worldwide.

D. It can remove dangerous metals in the water.

49. Which of the following shows that the shortage of clean water is a serious problem?

A. Forty million packets of the treatment have been given to countries for free.

B. Delegates from about 130 nations attended the Fourth World Water Forum.

C. Four grams of chemicals can treat liters of dirty water for a low cost.

D. Infections from dirty water kill several thousand children every day.

50. The best title for this article is ______.

A. A Small Packet of Chemicals, a Big Effect on Dirty Water

B. The Procter and Gamble Company and C.D.C.

C. The Shortage of Clean Water                           

D. How to Cure Diarrhea