Gas turbines differ from steam turbines in that （）.

Geothermal(地热)Energy
　　1 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

共用题干
第一篇

Renewable Energy Sources

Today petroleum（石油）provides around 40% of the world's energy needs, mostly
fuelling automobiles.Coal is still used,mostly in power stations,to cover one-quarter of our
energy needs,but it is the least efficient,unhealthiest and most environmentally damaging
fossil fuel（矿物燃料）.Natural gas reserves could fill some of the gap from oil,but reserves
of that will not last into the 22^nd century either. Most experts predict we will exhaust easily
accessible reserves within 50 years.Less-polluting renewable energy sources offer a more
practical long-term energy solution."Renewable"refers to the fact that these resources are
not used faster than they can be replaced.
Hydroelectric（水力发电的）power is now the most common form of renewable energy,
suDDIvina around 20%of world electricity.China's Three Gorges Dam is the largest ever.
At five times the size of the US's Hoover Dam, its 26 turbines（涡轮机）will generate the
equivalent energy of 18 coal-fired power stations.It will satisfy 3% of China's entire
electricity demand.
In 2003. the first commercial power station to use tidal（潮汐的）currents in the open
sea opened in Norway. It is designed like windmill（风车）,but others take the torm of
turbines.
As prices fall,wind power has become the fastest growing type of electricity
generation一quadrupling（翻两番）worldwide between 1999 and 2005. Modern wind farms
consist of turbines that generate electricity.Though it will be more expensive,there is more
than enoucih wind to provide the world's entire energy needs.Wind farms come in onshore
and offshore forms.They can often end up at spots of natural beauty,and are often
unpopular with residents.And turbines are not totally harmless一they can interfere with radar,
alter climate and kill sea birds.Scotland is building Europe's largest wind tarm,wnicn will
power 200.000 homes.The UK's goal is to generate one-fifth of power from renewable
sources,mainly wind,by 2020.But this may cause problems,because wind is unreiiable.

According to the passage,resources like wind are
A:renewable.
B:recyclable.
C:damaging.
D:scarce.

共用题干
Energy and Public Lands
The United States boasts substantial energy resources. Federal lands provide a good deal of US energy production,the US Department of the Interior manages federal energy leasing （租赁）both on land and on the offshore Outer Continental Shelf Production from these sources amounts to nearly 30 percent of total annual US energy production.
In 2000,32 percent of US oil,35 percent of natural gas,and 37 percent of coal were pro-duced from federal lands,representing 20,000 producing oil and gas leases and 135 producing coal leases. Federal lands are also estimated to contain approximately 68 percent of all undis-covered US oil reserves and 74 percent of undiscovered natural gas.
Revenues from federal oil,gas,and coal leasing provide significant returns to US taxpayers as well as State Government. In 1999,for example,$553 million in oil and gas revenues were paid to the US Treasury,and non-India coal leases accounted for over$304 million in revenues,of which 50 percent were paid to State governments. Public lands also play a critical role in energy delivery. Each year , federal land managers authorize（许可）rights of way for transmission lines , rail systems , pipe-lines,and other facilities related to energy production and use.
Alternative energy production from federal lands falls behind conventional energy pro-duction , though the amount is still significant. For example , federal geothermal（地热）re-sources produce about 7. 5 billion kilowatt-hours（千瓦时）of electricity per year,47 percent of all electricity generated from US geothermal energy. There are 2,960 wind turbines on public lands in California alone,producing electricity for about 300,000 people. Federal hydropower （水电）facilities produce about 17 percent of all hydropower produced in the United States.
Because of the growing US thirst for energy and increasing public unease with depend-ence on foreign off sources,pressure on public lands to meet US energy demand is becoming more intense. Public lands are available for energy development only after they have been evaluated through the land use planning process.If development of energy resources conflicts with management or use of other resources,development restrictions or impact moderation measures may be enforced,or mineral be banned altogether.

Geothermal resources,wind turbines,and hydropower facilities in Paragraph 4 are ci-ted as examples to illustrate that______.
A: alternative energy production is no less than conventional energy production
B: they are the most typical conventional energy resources from public lands
C: geothermal resources are more important than the other two
D: the amount of alternative energy production from public lands is huge

共用题干
第一篇

Renewable Energy Sources

Today petroleum（石油）provides around 40% of the world's energy needs, mostly
fuelling automobiles.Coal is still used,mostly in power stations,to cover one-quarter of our
energy needs,but it is the least efficient,unhealthiest and most environmentally damaging
fossil fuel（矿物燃料）.Natural gas reserves could fill some of the gap from oil,but reserves
of that will not last into the 22^nd century either. Most experts predict we will exhaust easily
accessible reserves within 50 years.Less-polluting renewable energy sources offer a more
practical long-term energy solution."Renewable"refers to the fact that these resources are
not used faster than they can be replaced.
Hydroelectric（水力发电的）power is now the most common form of renewable energy,
suDDIvina around 20%of world electricity.China's Three Gorges Dam is the largest ever.
At five times the size of the US's Hoover Dam, its 26 turbines（涡轮机）will generate the
equivalent energy of 18 coal-fired power stations.It will satisfy 3% of China's entire
electricity demand.
In 2003. the first commercial power station to use tidal（潮汐的）currents in the open
sea opened in Norway. It is designed like windmill（风车）,but others take the torm of
turbines.
As prices fall,wind power has become the fastest growing type of electricity
generation一quadrupling（翻两番）worldwide between 1999 and 2005. Modern wind farms
consist of turbines that generate electricity.Though it will be more expensive,there is more
than enoucih wind to provide the world's entire energy needs.Wind farms come in onshore
and offshore forms.They can often end up at spots of natural beauty,and are often
unpopular with residents.And turbines are not totally harmless一they can interfere with radar,
alter climate and kill sea birds.Scotland is building Europe's largest wind tarm,wnicn will
power 200.000 homes.The UK's goal is to generate one-fifth of power from renewable
sources,mainly wind,by 2020.But this may cause problems,because wind is unreiiable.

According to the passage,which of the following is the most polluting energy resource?
A:Petroleum.
B:Coal.
C:Natural gas.
D:Water.