什么是生活垃圾的资源化？
参考答案：
生活垃圾的资源化是指采取管理和工艺措施从生活垃圾中回收物质和能源，加速物质和能源的循环，创造经济价值的方式。主要包括以下三方面：物质回收、物质转换和能源回收。
物质回收主要是指将纸类、塑料、金属、玻璃等生活垃圾中化学稳定物质直接回收，用于生产再生产品；
物质转换，即利用废物制取新形态的物质，如利用废玻璃和废橡胶生产铺路材料，利用炉渣生产水泥和其他建筑材料，利用有机垃圾堆肥等；
能源回收主要包括：
1）可燃性生活垃圾通过直接焚烧回收热能；
2）易降解有机生活垃圾通过厌氧发酵技术回收可作为燃料的沼气。
Directions: There are 4 passages in this part. Each of the passages is followed by ,5 questions or unfinished statements. For each of them there are 4 choices marked A, B, C and D. Choose the best one and mark your answer on the ANSWER SHEET with a single line through the center.
Passage One
| In science, a theory is a reasonable explanation of observed events that are related. A theory often involves an imaginary model that helps scientists picture the way an observed event could be produced. A good example of this is found in the kinetic (运动的) molecular theory, in which gases are pictured as being made up of many small particles that are in constant motion. A useful theory, in addition to explaining past observations, helps to predict events that have not as yet been observed. After a theory has been publicized, scientists design experiments to test the theory. If observations confirm the scientists’ predictions, the theory is supported. If observations do not confirm the predictions, the scientists must search further. There may be a fault in the experiment, or the theory may have to be revised or rejected. Science involves imagination and creative thinking as well as collecting information and performing experiments. Facts by themselves are not science. As the mathematician Jules Henri Poincare said: "Science is built with facts just as a house is built with bricks, but a collection of facts cannot be called science anymore than a pile of bricks can be called a house. " Most scientists start an investigation by finding out what other scientists have learned about a particular problem. After known facts have been gathered, the scientist comes to the part of the investigation that requires considerable imagination. Possible solutions to the problem are formulated. These possible solutions are called hypotheses. In a way, any hypothesis is a leap into the unknown. It extends the scientist’s thinking beyond the known facts. The scientist plans experiments, performs calculations, and makes observations to test hypotheses. For without hypotheses, further investigation lacks purpose and direction. When hypotheses are confirmed, they are incorporated into theories. |
In the fourth paragraph, the author implies that imagination is most important to scientists when they ______.
A．gather known facts
B．formulate possible solutions to a problem
C．evaluate previous work on a problem
D．close an investigation