The sun's energy provides us with all EXCEPT _______.

A . is nearest to the Earth B . is farthest from the Earth C . is on the opposite side of the Earth from the Moon D . and Moon and Earth are in line

A . and Moon and Earth form a right angle B . and Moon and Earth are in line C . crosses the celestial equator D . is farthest from the Earth

A . Impeller B . Electric motor C . Volute D . Eye

A . convert B . store C . utilize D . receive

A.one tenth B.one millionth C.all that comes from the surface of the sun D.a very small portion

A．Right B．Wrong C．Not mentioned

W: Maybe you're missing the point of this physics study group. Q: What does the woman mean？ (19) A．She holds the same view with the man. B．The man missed the last study session. C．She didn't understand the last chemistry class. D．The man should be more serious about his studies.

Two of them are【C2】______while the other six【C3】______from the sun than the earth is. The farther they are, the longer【C4】______they【C5】______around the sun. People noticed long ago that these traveling bodies moved around in the sky【C6】______definite paths. It is a【C7】______called gravity that【C8】______them in their paths. We know that every little bit of matter in the【C9】______pulls upon every other bit of mater. The pull between two bodies is【C10】______to the product of their masses. Because the sun is so large that pulls【C11】______the sun and the planets are thus great. If it【C12】______not for these pulls, the planets【C13】______off into space. In the same way【C14】______exists a pull between the earth and the moon, which keeps the moon【C15】______in its orbit around our planet, the earth. The gravity holds you to its surface, and pulls back to it the ball which you【C16】______into the air. Of course the ball also pulls【C17】______the larger earth, but the earth is so much larger that the pull【C18】______. Now remember that large bodies exert a greater pull on any body than smaller ones which contain【C19】______material. But each object in the universe, no matter how small, pulls on all other objects【C20】______extent. 【C1】 A．thing B．body C．matter D．substance

A Because bullocks have long been used by Indian people B Because bullocks walk slowly and are easy to control C Because there are few non-working bullocks in India D Because there is not enough oil in India

A．Petroleum B．Solar power C．Coal D．Natural gas

A) Primitive B) Exhaustible C) Cheap D) Unsafe

A.the burning of the fuel; medium shaft B.fuel spray; fresh air C.fuel; fuel spray D.the burning of the fuel; the burned gas mixture

A) condition B) prospect C) outlet D) anticipation

A．absorbed by the clouds in the lower atmosphere B．reflected by the gases in the upper atmosphere C．lost in the upper and lower atmosphere D．used to evaporate water from the oceans and lakes

Two kinds of systems generate solar energy: passive and active. A passive solar energy system generates energy from fixed glass plates built into the structure, without the use of mechanical devices. A greenhouse is a good example of a building heated by passive solar energy. The sun's rays penetrate the glass panels to heat the interior of the greenhouse, and the heat is retained through tight construction. The same principle can be applied to heating homes and other buildings on sunny days. An active solar energy system makes use of mechanical devices and moving parts to maximize the amount of energy collected. For example, solar energy can be generated with photovoltaic cells, which are made from silicon, an abundant element. A bank of photovoltaic cells can be encased in glass and wired together to produce electricity. The bank of cells can be mounted on the roof at an angle that maximizes exposure to direct sunlight. Another device to generate solar energy is a flatplate collector, which is an insulated glass box, typically placed on the sun-facing roof. Inside the box are pipes filled with air or water. The heat that builds up in the pipes can be used for home heating and hot-water supplies. Two questions persist about solar energy: How can solar energy be used in colder climates？ How can solar energy be used on cloudy days？ Scientists have the technological means to overcome both problems, but the solutions may make solar energy more expensive for many people than other alternatives. The energy released from the sun is about 10,000 degrees F, but by the time the rays reach the earth the temperature is considerably lower, because the sun's energy has diffused over a large area during its long journey. To be useful energy in colder climates, the sun's diffused rays must be concentrated. The process of concentrating the sun's rays is not difficult. Scouts learn that sunlight focused with a lens at the proper angle can burn a piece of paper. In warmer climates, the sun's rays can provide heat and hot water with little concentration. In colder climates, compensation is made simply by collecting more of the sun's rays by building a larger collecting device and rotating the lenses as the sun's position in the sky changes. In cloudy weather, another system can store the energy generated from the sun. For example, water heated by the sun can be retained in protected storage containers. Because of high installation coasts, solar energy is more expensive than other sources of energy for most consumers. At this time, electricity provided by a solar power plant costs two or three times the amount of a coal-fired plant. But solar equipment is generally installed on the consumer's roof rather than at a central power plant, as is the case with other energy sources. A family must pay several thousand dollars to construct a solar energy system capable of providing virtually all household heat and electricity. The family is also responsible for maintenance and repair of the system. While initial construction costs are much higher, monthly heating and electricity bills are much lower once the system begins operation. Users of solar energy do not face rising monthly electricity bills from a power company, which passes to its consumers the increasing costs of purchasing fossil fuels and constructing new facilities. Solar energy is economical for consumers who remain in the same house for many years and can benefit from low monthly operating costs. For most families, solar energy will become more attractive when other energy sources become more expensive. One indication of solar energy's bright future is that petroleum companies have bought the m A．The technical problem of providing heat on cloudy days are not yet solved. B．It costs much to have a solar energy system installed at home. C．There are basically two types of solar energy. D．Solar energy is clean, inexhaustible and free of risk.

A．harnessing B．aiming C．assisting D．attempting

A. convert B. store C. utilize D. receive

1.A.number B.group C.price D.deal 2.A.effect B.amount C.course D.program 3.A.increase B.increasing C.had increased D.is increasing 4.A.without B.improve C.producing D.strength 5.A.key B.a direction C.a solution D.service 6.A.cost B.method C.branch D.pound 7.A.Show B.pay C.save D.produce 8.A.property B.remedy C.welfare D.movements 9.A.So that B.which C.whose D.Of which 10.A.at B.for C.In D.from

A．filteringB:filling