第二部分阅读理解（共两节，满分40分） 第一节（共15小题；每小题2分，满分30分） 阅读下列四篇短文，从每小题后所给的A、B、C、D四个选项中，选出最佳选项，并在答题卡上将该选项。 A The Greenbelt, a wide belt of open land around the cities and towns of the San Francisco Bay Area, includes about 3.75 million of the Bay Area’s 4.5 million acres. The Bay Area Greenbelt is one of the largest areas of open land in any U.S. urban   area. Open land is land that has few buildings and lots of natural areas. The Greenbelt’s open land includes parks, forests, beaches, and more than 8,500 farms. What are the advantages of the Greenbelt? The Greenbelt has many advantages for people in the Bay Area, which include: walking and biking areas close to the cities and towns; places for wild plants and animals; cleaner air and water; and income from farms. Is the Greenbelt in danger? Five hundred seventy thousand acres of the Greenbelt are in danger. There are builders who want to build suburbs on them. If those acres become suburbs, many things will change: the urban and suburban area will almost double; many farms will disappear; traffic will become worse; and the air will become dirtier. What is Greenbelt Alliance (联盟)? Greenbelt Alliance, an organization that saves land in the San Francisco Bay Area, works alone and with other groups to save the Greenbelt in four ways: Try to persuade people to build new buildings on land that is already urban, not on open land. Make sure that the city and town governments are all making plans to save the Greenbelt. Help Bay Area towns and cities to buy pieces of open land to make into natural areas. Teach people in the Bay Area why the Greenbelt is important and what they can do to help save it. 46. What can we learn about the Greenbelt from the first paragraph? A. The Greenbelt is the largest open land in the United States. B. The Greenbelt covers much more than half of the Bay Area. C. There are few farms on the open land of the Greenbelt. D. There are more than 8,500 natural areas on the Greenbelt. 47. One of the advantages of the Greenbelt for people in the Bay Area is __________. A. convenience for exercise                    B. income from sightseeing C. cleaner city streets                             D. more plants and animals 48. The Greenbelt is in danger because __________. A. traffic is getting worse                        B. some plan to build suburbs on it C. the suburban area has doubled         D. pollution is becoming serious 49. Which of the following is TRUE about Greenbelt Alliance? A. It builds new buildings on open land. B. It buys large open land for the Bay Area. C. It educates people how to save the Greenbelt. D. It helps the city governments make plans.