第3部分：概括大意与完成句子(第23——30题，每题1分，共8分)

Geothermal(地热)Energy

1 Since heat naturally moves from hotter regions tocooler ones， the heat fromthe earth's center flows outwards towardsthe surface。 In this way， it transfersto the next layer of rock。 If the temperatureis high enough， some of this rockmelts and forms magma(岩浆)。 The magmaascends in its turn towards the earth'ssurface。 It often remains well below the earth's surface， creating vast areasofhot rock。 In such regions， there are deep cracks， which allow rainwater todescend underground。 Some of the heatedrainwater travels back up to the earth'ssurface where it will appear as a hotspring。 However， if this ascendinghot waterreaches a layer of impermeable(不可渗透的)rock， it remains trapped， forming ageothermal reservoir。 If geothermalreservoirs are close enough to the surface，they can be reached by drilling wells。 Hot water and steamshoot up the wellsnaturally， and can be used to produce electricity in geothermalpower plants。

2。A few geothermal power plants depend on dry-stemreservoirs which producesteam but little or no water。 In these cases， the steam is pipedup directly toprovide the power to spin a turbine generator。 The first geothermalpower plant，constructed at Lardarello in Italy， was of this type， and is stillproducingelectricity today。

3。Most currently operating geothermal power plants areeither "flash" steamplants or binary(双重的)plants。 Flash plants produce mainly hot water rangingintemperature from 300° to 700°Fahrenheit。 This water is passed through one ortwo separators wherereleased from the pressure of the underground reservoir，it"flashes" or boils into steam Again， the force of this steam provides theenergy to spin theturbine and produce electricity。 The geothermal water andsteam are then reinjecteddirectly back down into the earth to maintain thevolume and pressure of thereservoir。 Gradually they will be reheated and canthen be usedagain。

4。A reservoir with temperatures below 300° Fahrenheit is nothot enough toflash steam but it can still be used to generate electricity inbinary fluid。 Thesteam from this is used to power the turbines。 As in the flashsteam plant， thegeothermal water is recycled back into the reservoir。

23.Paragraph 1_____E____

24.Paragraph 2____F_____

25.Paragraph 3____C_____

26.Paragraph 4____B_____

A. Recyclable water and steam

B. Binary plants

C. Flash steam plants

D. Generation of electricity

E. Origin of geothermal energy

F. Dry steam plants

27. A geothermal reservoir is formed when hot water is trappedunder__B____.

28. A dry-steam reservoir produces steam with___C___.

29. Flash plants produce hot water through___E___.

30. In a binary plant, the heat of the geothermal water can beconvertedinto__F____.

A. hot springs

B. impermeable rock

C. little or no water

D. turbine operator

E. one or two separators

F. the energy to turn a turbine

参考答案：EFCBBCEF