题目内容
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[单选题]
In gasoline engines（）are used to ignite the fuel-air mixture,producing the power.
A.3-side rotor
B.gasoline
C.spark plugs
D.diesel
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题目内容
（请给出正确答案）
如果结果不匹配，请 联系老师 获取答案
题目内容
（请给出正确答案）
A.3-side rotor
B.gasoline
C.spark plugs
D.diesel
如果结果不匹配，请 联系老师 获取答案
更多“In gasoline engines（）are used …”相关的问题
Policymakers and industry have four options: reduce vehicle use, increase the efficiency and reduce the emissions of conventional gasoline-powered vehicles, switch to less harmful fuels, or find less polluting driving systems. The last of these -- in particular the introduction of vehicles powered by electricity -- is ultimately the only sustainable option. The other alternatives are attractive in theory but in practice are either impractical or offer only marginal improvements. For example, reduced vehicle use could solve traffic problems and a host of social and environmental problems, but evidence from around the world suggests that it is very difficult to make people give up their cars to any significant extent. In the US, mass transit ridership and carpooling have declined since World War Ⅱ. Even in western Europe, with fuel prices averaging more than $1 a liter (about $ 4 a gallon) and with easily accessible mass transit and dense populations, cars still account for 80 percent of all passenger travel.
Improved energy efficiency is also appealing, but automotive fuel economy has barely made any progress in 10 years. Alternative fuels such as natural gas, burned in internal-combustion engines, could be introduced at relatively low cost, but they would lead to only marginal reductions in pollution and greenhouse emissions (especially because oil companies are already spending billions of dollars every year to develop less polluting types of gasoline).
From the passage we know that the increased use of cars will ______.
A．consume half of the oil produced in the world
B．have serious consequences for the well-being of all nations
C．widen the gap between the developed and developing countries
D．impose an intolerable economic burden on residents of large cities
A typical combustion process is the burning of gasoline in an automobile engine. The vaporized fuel is mixed with air, compressed in the engine's cylinder, and ignited by a spark. As the fuel flame up, the heat produced flows into the adjacent layer of unburned fuel and ignites it. In this way a zone of fire spreads throughout the fuel mixture is called a combustion wave.
The speed at which such a combustion wave travels through a fuel mixture is called the burning velocity of the mixture. The burning velocity of a gas such as methane quietly burning in air is only about one foot per second. By comparison, the burning velocity of more reactive combinations such as the rocket Fuels, hydrogen and fluorine, can be hundreds of feet per second.
If the fuel flows at the same speed as the combustion wave, the result is a stationary flame, like the one in your kitchen gas burner. In the kitchen burner a jet of gas mixed with airflows from the opening in the head of the burner. If the velocity of the fuel mixture flowing from the opening is greater than its burning velocity, the flame blows out.
In jet engines speeding through the air at 500 to 600 miles per hour, the engine's flame is sometimes blown out by the blast of air entering the combustion chamber at high speeds. Jet pilots call this condition "flameout".
Combustion can sometimes occur very slowly. A familiar example of slow combustion is the drying of ordinary oil-based paint. In this chemical reaction, called oxidation, the oxygen in the air reacts with the drying oil in the paint to provide a tough film. The linseed oil molecules link together, forming an insoluble coating.
How can the chemical reaction involved in such a quiet process as the drying of paint also produce spectacular flames and explosions？ The main difference between the two is the temperature at which they occur.
At lower temperatures the reaction must take place over a long time. The heat which is slowly produced is dissipated to the surroundings and does not speed up the reaction. When the heat produced by the low-temperature reaction is retained instead of being dissipated, the system breaks into flame.
In a flame or explosion, the reactions are extremely fast. In many chemical processes, however, such a rapid oxidation process would be extremely destructive.
Which of the following states the major difference between oxidation and fire？
A．Their burning velocities differ in rate.
B．Oxidation is a chemical reaction while fire is a physical reaction.
C．Oxidation does not create heat.
D．They occur at different temperatures.
A．be somewhat lighter in total body weight than a conventional vehicle fueled with gasoline
B．have a larger and more powerful engine than a conventional vehicle fueled with gasoline
C．average more miles per gallon than a "gasoline alone" vehicle fueled With methanol
D．have a larger and heavier fuel tank than a "gasoline alone" vehicle fueled with methanol
A.air
B.gasoline
C.diesel
D.fuel-air mixture
A．the combustion of gasoline releases photo chemically active hydrocarbons
B．the combustion of gasoline involves an intricate series of reactions
C．gasoline molecules have fewer carbon-carbon bonds
D．gasoline is a carbon-based fuel with smaller molecules
A diesel engine is similar to a gasoline engine except that the former has no _____.
A.cross-head
B.cylinder
C.connecting rod
D.spark plug
A． approached
B． to approach
C． approach
D． approaching
Fire engines and ambulances have ______ over othertraffic.
A) priority
B) urgency
C) superiority
D) emergency
Solid-fuel engines are simpler than liquid-fuel engines, ______have important uses.
A．both of them
B．both
C．both of which
D．both all
The search engines work by means of _________.
A． arranging links to the Internet
B． submitting specific search term
C． updating a knowledge database
D． searching engine spiders
