题目内容
（请给出正确答案）
A.be established
B.be sent
C.be covered
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更多“Cleaner heating system will in Beijing to control air pollution.A、be establishedB、be sen”相关的问题
In addition to low fuel bills, many people choose these stoves because their initial cost is very low (the prices range from $ 50 kits to $ 5,000 top-of-the-line models), and because new technology has made wood fires more efficient, cleaner, and, therefore, safer than ever before.
One new technological feature of this type is the catalytic(催化) combustor which adds about $ 100 to $ 200 to the cost of the stove, but which causes much more complete combustion (燃烧) of the wood and therefore bums up more of the pollutants left by incomplete combustion and produces more heat.
A second cost-saving innovation is a device which agitates the wood, increasing the amount of oxygen that reaches the center of the wood pile, and leading to more efficient combustion. The real advantage of this device is that it allows the owner to make use of cheap sources of wood such as dirty wood chips (an industrial by-product) that have almost no commercial value, cost as little as $ 20 a ton, and burn very inefficiently in furnaces without an agitator.
According to the passage, the number of wood-burning stove sold for home use ______.
A．went up fivefold over a six-year period
B．rose to seven million during the seventies
C．multiplied thirty-five times between 1973 and the beginning of 1981
D．increased by 6,000,000 over an eight-year period
A.pictographique
B.idéographique
C.idéophonographique
D.logographique
The second paragraph suggests strongly______.
A．the contradictory nature of the patent system
B．the importance of the patent system
C．the benefits of the patent system
D．the monopoly of the patent system
A.1
B.2
C.2.5
D.3
Why sharks are useful for humans.*
A．Their tasty meat.
B．The principle of their defense system against disease.
C．Their solid skin.
D．The principle of their birth modes.
The(72)has several major components, including the system kernel, a memory management system, the file system manager, device drivers, and the system libraries.
A．application
B．information system
C．operating system
D．iterative
According to this passage, which is the best title？
A．Teachers and Actors
B．Educational System
C．A Good Teacher
D．How to Become a Good Actor
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