英语高手请进帮忙做几个单选,多谢了

题目

英语高手请进帮忙做几个单选,多谢了
7-11 单选题
7 There are different ways in which people try to deal with the problem of energy. One way is the greater production of common energy sources, such as coal, oil and gas. The trouble with these sources, however, is that they are not renewable.
Another way is energy conservation (节能), which means using energy more efficiently (有效地). In some very cold countries people build special houses to save energy. They place materials between the inside and the outside of the walls of the house to keep the cold out and the warmth in. The house is heated by the lights, the body heat of the people and the other equipment in it.
Finally, renewable energy sources are used even though they are often expensive to develop. One form of these is geothermal energy. In certain parts of the world the temperature of the earth increases thirty degrees centigrade with each kilometer down. At six kilometers, therefore, it rises to nearly two hundred degrees. To get the he

答案

7.C
8.C
9.A
10.C
11.D