The energy which the sun radiates goes in every direction, and only a minute part of it falls on the earth Even so, it represents power of about 5,000,000 horsepower (马力) per square mile per day; the sun gives us as much energy every miunte as mankind utilizes in a year At present,we use this energy indirectly, and it is our final source of power Coal represents the chemical action of the sun on green plants thousands of years ago Water power results from the rain formed by vapor which comes from the evaporation of water under the sunshine Even windmills operate because of air currents set in motion by the different heating affects of the sun in different places Some day, through chemistry or some type of solar engine, we shall harness this great source of energy more directly Already a scientist has worked out an engine, surprisingly efficient, in which the suns rays are concentrated through mirrors on a tube of water to create steam
1How much energy given off by the sun reaches the earth?
A100% but indirectly B5%
C50% Donly a very tiny amount
2The reason why all the solar energy falling on the earth cant be utilized is that
Aonly a very small part is available
Bthe sun is too distant from the earth
Cit takes thousands of years for this energy to be stored up in coal and oil
Dour scientific knowledge is not sufficient
3Which of the following statements is NOT true?
AEven windmills action depends on the sun.
BThe sun produces enormous energy for man to make use of.
CSome day man will be able to utilize 100% of the solar energy that gets to the earth.
DThe sun produces different heating effects in different places.
4In order to support this argument, the writer gives the example that
Aa machine using solar energy efficiently has already been developed
Bthe sun is our final source of power
Cman uses only a tiny part of the suns energy
Dthe part of the suns energy we use is used indirectly
答案：1D 2D 3 C 4A
