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[单选题]

As a source of power, water is virtually inexhaustible. （)

A.inaccessible

B.insufficient

C.abundant

D.extinguishable

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发布时间：2022-08-19

更多“As a source of power, water is virtually inexhaustible. （)”相关的问题

第1题

The primary winding is connected to（）.

A.the power source

B.the measurement instrument

C.the motor

D.the load

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第2题

This passage centers mainly on ______ .A．harnessing energy through chemistryB．our last sou

This passage centers mainly on ______ .

A．harnessing energy through chemistry

B．our last source of power

C．how water power is produced

D．the amount of solar energy that can be utilized

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第3题

Nuclear energy, despite its early promise a source of eleetrical power, is still under dis

pute____old and safe energy sources.

A.in compared with

B.in compared to

C.compared with

D.compared to

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第4题

In order to support this argument, the writer gives the example that ______ .A．a machine u

In order to support this argument, the writer gives the example that ______ .

A．a machine using solar energy efficiently has already been developed

B．the sun is our final source of power

C．man uses only a tiny part of the sun's energy

D．the part of the sun's energy we use is used indirectly

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第5题

Successful innovations have driven many older technologies to extinction and have resulted

In 1870, horses and mules were the prime source of power on U. S. farms. One horse or mule was required to support four human beings—a ratio that remained almost constant for many decades. At that time, had a national commission been asked to forecast the horse and the population for 1970, its answer probably would have depended on whether its consultants were of an economic or technological turn of mind. Had they been "economists" , they would probably have projected the 1970 horse or mule population to be more than 50 million. Had they been "technologists", they would have recognized that the power of steam had already been harnessed to industry and to land and ocean transport. They would have recognized further that it would be the prime source of power on the farm. It would have been difficult for them to avoid the conclusion that the horse and mule population would decline rapidly.

According to the passage, what supplied most of the power on U. S. farms in 170？

A．Animals.

B．Humans.

C．Engines.

D．Water.

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第6题

Successful innovations have driven many older technologies to extinction and have resulted

in higher productivity, greater consumption of energy, increased demand for raw materials, accelerated flow of materials through the economy and increased quantities of metals and other substances in use per person. The history of industrial development is full of examples. In 1870, horses and mules were the prime source of power on U.S. farms. One horse or mule was required to support four human beings--a ratio that remained almost constant for many decades. At that time, had a national commission been asked to forecast the horse and mule population for 1970, its answer probably would have depended on whether its consultants were of an economic turn of mind. Had they been "economists", they would have recognized that the power of steam had already been harnessed to industry and to land and ocean transport. They would have recognized further that would be only a matter of time before steam would be the prime source of power on the farm. It would have been difficult for them to avoid the conclusion that the horse and mule population would decline rapidly.Which of the following is NOT mentioned by the author as a consequence of new technological developments？A.Older technologies die away.B.The quality of life is improved.C.Overall productivity increases.D.More raw materials become necessary.

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第7题

The energy which the sun radiates goes in every direction, and only a minute part of it fa

lls on the earth. Even so, it represents power of about 5,000,000 horsepower (马力)per square mile per day; the sun gives us as much energy every minute as mankind utilizes in a year. At present, we use this energy in directly, and it is our final source of power. Coal represents the chemical action of the sun on green plants thousands of years ago. Water power results from the rain formed by vapor which comes from the evaporation of power. Coal represents the rain formed by vapor which comes from the evaporation of water under the sunshine. Even windmills operate because of air currents set in motion by the different heating affects of the sun in different places. Some day, through chemistry or some type of solar engine, we shall harness this great source of energy more directly. Already a scientist has worked out an engine, surprisingly efficient, in with the sun' s rays are concentrated through mirrors on a tube of water to create steam.

How much energy given off by the sun reaches the earth？

A．100 % but indirectly

B．5 %

C．0.5

D．only a very tiny amount

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第8题

Some pessimistic experts feel that the automobile is bound to fall into disuse. They see a

day in the not-mo-distant future when all autos will be abandoned and allowed to rust. Other authorities, however, think the auto is here to stay. They hold that the car will remain a leading means of travel in the foreseeable future.

The motorcar will undoubtedly change significantly over the next 30 years. It should become smaller, safer, and more economical, and should not be powered by the gasoline engine. The car of the future should be far more pollution-free than present types.

Regardless of its power source, the auto in the future will still be the main problem in urban traffic congestion(拥挤). One proposed solution to this problem is the automated highway system.

When the auto enters the highway system, a retractable(可伸缩的) arm will drop from the auto and make contact with a rail, which is similar to those powering subway trains electrically. Once attached to the rail, the car will become electrically powered from the system, and control of the vehicle will pass to a central computer. The computer will then monitor all of the car's movements.

The driver will use a telephone to dial instructions about his destination into the system. The computer will calculate the best route, and reserve space for the car all the way to the correct exit from the highway. The driver will then be free to relax and wak for the buzzer(蜂鸣器) that will warn of his coming exit. It is estimated that an automated highway will be able to handle 10,000 vehicles per hour, compared with the 1,400 to 2,000 vehicles that can be carried by a present-day highway.

One significant improvement in the future car may probably be ______.

A．its power source

B．its driving system

C．its monitoring system

D．its seating capacity

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第9题

When aluminum was first produced about a hundred and fifty years ago, it was so difficult

to separate from the ores(矿石) in which it was found that its price was higher than that of gold. The price remained high until a new process was discovered for refining the metal with the aid of electricity approximately three quarters of a century later. The new method was so much cheaper that aluminum became practical for many purposes, one of which was making pots and pans.

Aluminum is lightweight, rustproof and easily shaped into different forms. By mixing it with other metals, scientist have been able to produce a variety of alloys, some of which have the strength of steel but weigh only one third as much.

Today, the uses of aluminum are innumerable. Perhaps its most important use is in transportation. Aluminum is found in the engines of automobiles, in the hulls of boats. It is also used in many parts of airplanes. In fact, the huge "airbus" planes would probably never have been produced if aluminum did not exist. By making vehicles lighter in weight aluminum has greatly reduced the amount of fuel needed to move them. Aluminum is also being used extensively in the building industry in some countries.

Since aluminum is such a versatile(多用的) metal, it is fortunate that bauxite(铝土矿) , which is one of its chief sources, is also one of the earth's most plentiful substances. As the source of aluminum is almost inexhaustible, we can expect that more and more uses will be found for this versatile metal.

The price of aluminum was sharply reduced when people discovered a new refining process with the aid of______.

A．wind power

B．solar energy

C．hydraulic power

D．electricity

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第10题

From the beginning rivers have played an important part in the life of man. Man of the ear

liest times used the rivers as a means of travel. Today rivers still serve as a great waterway for the transport and people.

In ancient times, man settled near rivers or on fiver banks and built up large empires.

Water is Nature’s most precious gift to man. Man needs water to irrigate his crops, to cook and to wash. In nations all over the world rivers mean life and wealth. They feed and clothe the nations around them.

Water is also a source of energy and power. Man constructs huge dams across the river to control the water for irrigation and get the energy needed to drive generators. The electrical power is then directed to homes, cities, factories and television stations.

Man uses water each day. His main source of water comes from reservoirs, which in turn get their water from the rivers.

Rivers also bring down soil and minerals from the mountains and deposit them on the plains building up rich fiver deltas for raising plants and crops. Fresh water life in rivers or in lakes fed by them provide man with food.

In a small way rivers help to keep man in good health and provide for his amusements. Various forms of water sports keep man strong and healthy.

Rivers have run on this earth long before man. Man’s future ability to live is uncertain, but rivers will flow on forever.

Rivers have been important to man ______.

A．since the last century

B．for a very long time

C．since a few hundred years ago

D．since a few years ago

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