5．As the development of the economy（经济） and the population growing，a lack （缺乏） of energy（能量） becomes more and more serious．In the modern world，we can't live without energy．But do you know where energy comes from？
Nearly all energy comes from the sun，either in a roundabout （不直接的） way or straight from it，in the form of heat rays and light rays（光线）．The light from the moon also comes from the sun．The moon can be said to be like a large mirror which throws back the sun's light to the earth．
Electrical energy comes from the sun in a roundabout way．For example，it can come from the power of water falling down a mountain．The water falls there as rain，and we know that rain is made by the sun's heat evaporating on the earth's surface．This water steam rises，condenses （凝结） on cooling，and falls as rain．The light and heat energy from coal also comes from the sun in a roundabout way．Coal was made by the rocks pushing on trees and plants which died millions of years ago．Those trees and plants grew with the help of sunlight，changing the sun's energy into chemical energy．When we burn coal，some of this energy is set free．
Energy which we use to drive cars comes from petrol，which was also made with the help of the sun in a roundabout way．Plants and animals which ate the plants，died millions of years ago，and the parts of them that were left were pushed under the rocks in the earth．These parts left from dead animals and plants made petroleum （原油），from which petrol and oil are now formed．
In this way，we can say that the sun is the place where nearly all energy comes from，and that without the sun's heat and light，there could be no life on earth．
根据短文内容选择最佳答案．
46．The light and heat energy from coal comes fromA．
A．the sun
B．the moon
C．the earth
47．The underlined word"evaporating"in the passage means"B"in Chinese．
A．挥发
B．蒸发
C．冷却
48．According to the passage，PictureAis right．
49．Which of the following is TRUE according to the passage？C
A．It takes billions of years to form coal or petrol
B．The writer talks about five kinds of energy
C．Nearly all energy comes from the sun，either in a roundabout way or straight from it，in the form of heat rays and light rays．
50．Which is the best title for the passage？B
A．THE SUN
B．ENERGY
C．A SERIOUS PROBLEM．
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