单选题
All useful energy at the surface of the earth comes from the activity of the sun. The sun heats and feeds mankind. Each year it provides men with two hundred million tons of grain and nearly ten million tons of wood. Coal, oil, natural gas, and all other fuels are stored-up energy from the sun. Some was collected by this season's plants as carbon compounds. Some was stored by plants and trees ages ago. Even waterpower derives from the sun. Water turned into vapor by the sun falls as rain. It courses down the mountains and is converted to electric power. Light transmits only the energy that comes from the sun's outer layers, and much of this energy that is directed toward the earth never arrives. About nine-tenths of it is absorbed by the atmosphere of the earth. In fact, the earth itself gets only one half-billion of the sun's entire output of radiant energy.
单选题
The sun is the source of all of the following EXCEPT ______. A. gasoline B. natural gas C. atomic energy D. green plants
单选题
Radiant energy is stored as carbon compounds by ______. A. plants B. rain C. rock D. wind
【正确答案】
A
【答案解析】[解析] 第二段中“Some was collected by this season's plants as carbon compounds.”碳的化合物是由植物转化而成的。因此选A。
单选题
The sun's energy directly provides us with ______. A. rain B. vapor C. light D. food
【正确答案】
C
【答案解析】[解析] 根据常识，由太阳直接提供的能源当然是C(阳光)，而不是其他。而且文章最后一段中也可找到相关内容：“Light transmits only the energy that comes from the sun's outer layers and much of this energy that is directed toward the earth never arrives.”
单选题
The largest part of the radiant energy directed toward the earth is ______. A. stored by the current season's plants B. absorbed by the earth's atmosphere C. turned into fuel D. used for electric power
【正确答案】
B
【答案解析】[解析] 在文章最后一段可找到“About nine-tenths of it is absorbed by the atmosphere of the earth.”可得出B是正确的。
单选题
Of the sun's entire output of radiant energy, the earth receives ______. A. one tenth B. nine tenths C. all that comes from the sun's outer layers D. a very small portion
【正确答案】
D
【答案解析】[解析] 文章最后一段提到“In fact, the earth itself gets only one half-billion of the sun's entire output of radiant energy.”五亿分之一是非常少的一部分，故答案是D。