阅读下列短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。

　　As the population of the planet increases, so does the number of homes, businesses, parking lots, schools, airports and roadways．all these structures use electricity and need to be lighted．Humans demand these lights．They want their homes more comfortable and they want their streets sage．The problem is that researchers are fin ding that all the light is having a negative effect on humans and wildlife as well．

　　Less than 10 years ago I drove to a thinly populated section of my town, lay down in the middle of the road and watched an attracted meteor shower(流星雨)．The area was short of homes, street lights and traffic．If I did that today, I wouldn't be able to see the meteor shower sa well, and I would surely be run over by a car．

　　Nowadays scientists are finding light pollution can be almost as bad as carbon dioxide pollution．if you've ever taken a flight at night, the view is beautiful, but you must remember that all the light you see is wasted electricity is worldwide．

　　Additionally, electricity needs to be generated, and the generation of electricity creates pollution by giving off greenhouse gases．This affects the air we breathe and our quality of life．

　　Scientists are also studying the effects of light pollution on wildlife．Thou sands of birds die each year when they crash into highly ighted buildings, as they become puzzled by the light．It has been long known that tiny sea turtle hatchings become lost and follow lights on the shore instead of heading towards the sea．

　　Fortunately, light pollution is one of the easiest sources of pollution that can be corrected without a negative effect．Following some guidelines and a little searching on Google can give you many ideas on how to reduce your contribution to light pollution．

完型填空

　　People do not analyze every problem they meet．Sometimes they try to remember a solution from the last time they had a 　　1　　 problem．They often accept the opinion or ideas of other people．Other times they begin to act without thinking; they try to find a solution by trial and error．　　2　　, when all of these methods fail, the person with a problem has to start analyzing．There are six 　　3　　 in analyzing a problem．

　　　　4　　 the person must recognize that there is a problem．For example, Sam's bicycle is broken, and he cannot ride it to class as he usually does．Sam must 　　5　　 that there is a problem with his bicycle．

　　Next the person must find the problem．Before Sam can repair his bicycle, he must know 　　6　　 it does not work．For example, he must determine the parts that are wrong．

　　Now the person must look for related 　　7　　 that will make the problem clearer and lead to 　　8　　 solutions．For example, suppose Sam decides that his bike does not work because there is something wrong with the brakes．　　9　　, he can look in his bicycle repair book and read about brakes, 　　10　　 his friends at the bike shop, or look at his brakes carefully．

　　After 　　11　　 the problem, the person should have 　　12　　 suggestions for a possible solution．Take Sam as an example 　　13　　, his suggestions might be：tighten or loosen the brakes; buy new brakes and change the old ones．

　　In the end, one 　　14　　 seems to be the solution to the problem．Sometimes the 　　15　　 idea comes quite 　　16　　 because the thinker suddenly sees something new or sees something in a 　　17　　 way．Sam, for example, suddenly sees there is a piece of chewing gum(口香糖)stuck to a brake．He 　　18　　 hits on the solution to his problem：he must 　　19　　 the brake．

　　Finally the solution is 　　20　　．Sam does it and finds his bicycle works perfectly．In short he has solved the problem．