单选题The author says that in some hot and dry areas it is advisable to _____.A build big lakes to store waterB construct big pumping stationsC channel water from nearby rivers to croplandD build small and cheap irrigation systems

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单选题

The author says that in some hot and dry areas it is advisable to _____.

build big lakes to store water

construct big pumping stations

channel water from nearby rivers to cropland

build small and cheap irrigation systems

更多“The author says that in some hot and dry areas it is advisab”相关问题

第1题

In the text, the author mainly deals with _________.［A］ the necessity of drama in a culture［B］ some social functions of dramas［C］ the responsibility of dramatists［D］ some key elements in drama-making

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第2题

Why is it necessary to extend ventilators of gasoline powered vessels to the bilges ________．A.To keep them dry，and thus easier to cleanB.To remove fuel vapors which are heavier than airC.To provide adequate air to the enginesD.To cool the machinery areas

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第3题

You are moving a gas free tank barge to dry dock for repairs．The barge must have onboard a valid ______．A.Gas Free CertificateB.Certificate of InspectionC.Permit to Proceed and Hot Work PermitD.All of the above

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第4题

Geothermal(地热)Energy1 Since heat naturally moves from hotter regions to cooler ones, the heat from the earth's center flows outwards towards the surface. In this way, it transfers to the next layer of rock. If the temperature is high enough, some of this rock melts and forms magma(岩浆). The magma ascends in its turn towards the earth's surface. It often remains well below the earth's surface, creating vast areas of hot rock. In such regions, there are deep cracks, which allow rainwater to descend underground. Some of the heated rainwater travels back up to the earth's surface where it will appear as a hot spring. However, if this ascending hot water reaches a layer of impermeable(不可渗透的)rock, it remains trapped, forming a geothermal reservoir. If geothermal reservoirs are close enough to the surface, they can be reached by drilling wells. Hot water and steam shoot up the wells naturally, and can be used to produce electricity in geothermal power plants.2.A few geothermal power plants depend on dry-stem reservoirs which produce steam but little or no water. In these cases, the steam is piped up directly to provide the power to spin a turbine generator. The first geothermal power plant, constructed at Lardarello in Italy, was of this type, and is still producing electricity today.3.Most currently operating geothermal power plants are either "flash" steam plants or binary(双重的)plants. Flash plants produce mainly hot water ranging in temperature from 300° to 700°Fahrenheit. This water is passed through one or two separators where released from the pressure of the underground reservoir, it "flashes" or boils into steam Again, the force of this steam provides the energy to spin the turbine and produce electricity. The geothermal water and steam are then reinjected directly back down into the earth to maintain the volume and pressure of the reservoir. Gradually they will be reheated and can then be used again.4.A reservoir with temperatures below 300° Fahrenheit is not hot enough to flash steam but it can still be used to generate electricity in binary fluid. The steam from this is used to power the turbines. As in the flash steam plant, the geothermal water is recycled back into the reservoir. 文章(23~30)Paragraph1_____A.Dry steam plants B.Binary plants C.Origin of geothermal energy D.Generation of electricity E.Flash steam plants F.Recyclable water and steam

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第5题

A dry-steam reservoir produces steam with _____.A.the energy to turn a turbine B.impermeable rock C.one or two separators D.turbine operator E.little or no water F.hot springs

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第6题

For example in the desert areas of the southwestern United States,the Indians cooked their food by beating it on a flat stone in the hot sun.They cooked pieces of meat and thin cakes of corn meal in this（）.A.zone B.sector C.method D.fashion

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第7题

The author says that he is a naturalist rather than a scientist probably because he thinks he__________.A.just reads about other people's observations and discoveries B.comes up with solution in most natural ways C.has a great deal of trouble doing mental arithmetic D.lacks some of the qualities required of scientist

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The author says that in some hot and dry areas it is advisab

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