第3部分：概括大意与完成句子(第23～30题，每题1分，共8分)

　　下面的短文后有2项测试任务：(1)第23-26题要求从所给的6个选项中为第2～5段每段选择1个最佳标题；(2)第27～30题要求从所给的6个选项中为每个句子确定1个最佳选项。

Natural Gas

　　Natural gas is produced from reservoirs deep beneath the earth's surface．It is a fossil fuel，meaning that it is derived from organic material buried in the earth millions of years ago.The main component of natural gas is methane(甲烷).

　　The popularity and use of clean natural gas has increased dramatically over the past 50 years as Dipeline infrastructure(基础设施)has been installed to deliver it conveniently and economically to millions of residential，commercial and industrial customers worldwide．Today，natural gas service is available in all 50 states，and is the leading energy choice for fueling American homes and indus-tries．More than 65 million American homes use natural gas．In fact，natural gas is the most eco-nomical source for home energy needs，costing one-third as much as electricity. In addition to heat-ing homes，much of the gas used in the United States is used as a raw material to manufacture a wide variety of products，from paint，to fibers for clothing，to plastics for healthcare，computing and fur-nishings． Natural gas is also used in a significant number of new electricity-generating power plants.

　　Natural gas is one of the safest and cleanest fuels available． It emits less pollution than other fossil fuels．dioxide(二氧化碳)and water vapor-the same substances emitted when humans ex-hale．Compared with some other fossil fuels，natural gas emits the least amount of carbon dioxide in-to the air when combusted(燃烧)-making natural gas the cleanest burning fossil fuel of all．The industry also is subject to substantial federal regulation in the areas of production and distribution，which help ensure it is provided to consumers safely and cleanly．

　　The United States consumes about one-third of the world's natural gas output，making it the lar-gest gas consuming region in the world．The U．S．Department of Energy's Energy Information Ad-ministration forecasts that natural gas demand will grow by more than 50 percent by 2025.

　　There are huge reserves of natural gas beneath the earth's surface．The largest reserves of natu-ral gas can be found in Russia，West and North Africa and the Middle East．LNG(液化天然气)has been produced domestically and imported in the United States for more than four decades.To-day，the leading importers of LNG are Japan，Korea，France and Spain.

　　同时按下Crtl键和A键查看答案
23．A 24．D 25．F 26．B 27．B 28．F 29．E 30．C