填空题

Natural Gas
1. 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.
2. The popularity and use of clean natural gas has increased dramatically over the past 50 years as pipeline infrastructure has been installed to deliver it conveniently and economically to millions of residential, commercial and industrial customers worldwide. Today, natural gas services available in all 50 states in the U.S., and is the leading energy choice for fueling American homes and industries. More than 65 million American homes use natural gas. In fact, natural gas is the most economical source for home energy needs, costing one-third as much as electricity. In addition to heating 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 furnishings. Natural gas is also used in a significant number of new electricity-generating power plants.
3. Natural gas is one of the safest and cleanest fuels available. It emits less pollution than other fossil fuel sources. When natural gas is burned, it produces mostly carbon dioxide and water vapour—the same substances emitted when humans exhale. Compared with some other fossil fuels, natural gas emits the least amount of carbon dioxide into the air when combusted, making natural gas the cleanest burning fossil fuel of all.
4. The United States consumes about one-third of the world’s natural gas output, making it the largest gas-consuming region in the world. The U.S. Department of Energy Information Administration forecasts that natural gas demand will grow by more than 50 percent by 2025.
5. There are huge reserves of natural gas beneath the earth’s surface. The largest reserves of natural gas can be found in Russia, West and North Africa and the Middle East. LNG has been produced domestically and imported in the United States for more than four decades. Today, the leading imports of LNG are Japan, Korea, France and Spain. Paragraph 4 ______.