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听力原文：M: I have to go to Professor Hudson's place to discuss my thesis. But if time allowed, I'd go to the movies with you when I come back the dorm.
W: It's too bad. I am going to the cinema right now with Jane, and I don't think you could make it.
Q: What is the man going to do？
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What can we learn about the device designed by David Whitten and Kirk Schanze？
Natural-gas Vehicles
Kermit the Frog once said, "It's not that easy be in green." Although he wasn't referring to cars, his observation seems particularly appropriate for the auto industry today: Designing, developing and marketing "green" cars has not been an easy task, which is why gasoline-powered vehicles still rule the road and fossil fuels still account for almost 75 percent of the world's energy consumption. As gasoline prices soar and concern over harmful emission mounts, however, cars that run on alternate fuel sources will become increasingly important. A natural-gas vehicle, or NGV, is the perfect example of such a car -- it's fuel-efficient, environmentally friendly and offers a relatively low cost of ownership.
Natural Gas Basics
The word "gas" is a confusing term because it is used to describe many different substances that are similar but not exactly the same. For example, the "gas" you put in your car is gasoline, one component of crude oil, or petroleum. Petroleum is a dark, sticky liquid mixture of compounds formed underground by the decay of ancient marine animals.
Natural gas also comes from the decay of ancient organisms, but it naturally takes a gaseous form. instead of a liquid form. Natural gas commonly occurs in association with crude oil. It is derived from both land plants and aquatic (水生的) organic matter and forms above or below oil deposits. It is often dissolved in crude oil at the high pressures existing in a reservoir. There are also reservoirs of natural gas, known as non-associated gas, that contain only gas and no oil.
Natural gas consists primarily of methane (沼气) and other hydrocarbon gases. Hydrocarbons are organic compounds composed only of the elements carbon and hydrogen. The hydrocarbons in natural gas are called saturated hydrocarbons because they contain hydrogen and carbon bound together by single bonds.
Like gasoline, natural gas is combustible (易燃的), which means it can be used in a combustion engine like gasoline. But cars that could burn natural gas didn't appear on the scene until the 1930s.
From Field to Ford
We extract natural gas trapped in underground reservoirs by drilling wells into the earth. A modern well. equipped with diamond-studded drill bits, can drill to depths approaching 25.000 feet.
Throughout the 19th century, the use of natural gas remained localized because there was no way to transport large quantities of gas over long distances, in 1890, the invention of a leakproof pipeline coupling made it possible to transport gas miles from the source. Improvements in pipeline technology continued over the next two decades until long-distance gas transmission became practical. From 1927 to 1931, ,laborers constructed more than t0 major natural gas transmission systems in the United States, making natural gas a viable energy source for many applications. The oil shortages of the late 1960s and early 1970s brought renewed interest in natural gas as a fuel source, especially for automobiles.
Today, owners of natural-gas vehicles can fill up their cars at one of 1,300 fueling stations located in the United States. Honda also offers a personal natural gas pump to people who purchase its natural-gas-powered Civic. The pump uses a home's existing natural gas lines and can be installed for $ 500 to $1500.
Natural-gas Vehicle Design
Natural-gas vehicles use the same basic principles as gasoline-powered vehicles. In other words, the fuel (natural gas in this case) is mixed with air in the cylinder of a four-stroke engine and then ignited by a spark plug to move a piston (活塞) up and down. Although there are some differences between natural gas and gasoline in terms of flamability and ignition temperatures, NGVs themselves operate on the same fundamental concepts as gasoline-powered vehicles.
Still, some
How many emerging-market companies will occur on the Fortune list within ten years？
My attitude to the hill has now changed. I used to【C2】______ as I approached it but now I tell myself the following. This hill will【C3】______ my heart and lungs and help me to lose weight and get【C4】______ . It will mean that I live longer. Finally as I wend my way up the incline I【C5】______ myself with the thought of all those silly people who pay money to go to a gym and sit on【C6】______ exercise bicycles when I can get the same【C7】______ for free. I have a smug smile of satisfaction【C8】______ I reach the top of the hill.
Problems are there to be faced and【C9】______ . We cannot achieve anything with an easy life. Helen Keller was the first deaf and blind person to gain a University degree. Her activism and writing proved inspirational. She wrote, "Character cannot be developed in ease and quiet.【C10】______ through experiences of trial and【C11】______ can the soul be strengthened,【C12】______ cleared, ambition inspired and success【C13】______ "
One of the main determinants of success in life is our attitude towards【C14】______ . From time to time we all face hardships, problems, accidents,【C15】______ and difficulties. Some are of our making but many confront us【C16】______ no fault of our own. Whilst we cannot choose the adversity we can choose our attitude towards it.
Douglas Bader was 21 when in 1931 he had both legs amputated following a flying accident. He was 【C17】______ to fly again and went on to become one of the leading flying aces in the Battle of Britain. He was a(n) 【C18】______ to others during the war. He said, "Don't listen to anyone who tells you that you can't do this or that.【C19】______ up your mind, you'll never use crutches or a stick, then have a go at everything. Go anywhere you want to. But never, never let them 【C20】______ you that things are too difficult or impossible."
【C1】
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