单选题：Electricity from WindA) Since 1980, the use of wind to prod

Electricity from Wind
A) Since 1980, the use of wind to produce electricity has been growing rapidly．In 1994 there were nearly 20,000 wind turbines worldwide, most grouped in clusters called wind farms that collectively produced 3,000 megawatts of electricity．Most were in Denmark ( which got 3 percent of its electricity from wind turbines) and California (where 17,000 machines produced 1 percent of the state's electricity, enough to meet the residential needs of a city as large as San Francisco)．In principle, all the power needs of the United States could be provided by exploiting the wind potential of just three states--North Dakota, South Dakota, and Texas.
B)Large wind farms can be built in six months to a year and then easily expanded as needed．With a moderate to fairly high net energy yield, these systems emit no heat-trapping carbon dioxide or other air pollutants and need no water for cooling; manufacturing them produces little water pollution．The land under wind turbines can be used for grazing cattle and other purposes, and leasing land for wind turbines
can provide extra income for farmers and ranchers.
C) Wind power has a significant cost advantage over nuclear power and has become competitive with coalfired power plants in many places．With new technological advances and mass production, projected cost declines should make wind power one of the world's cheapest ways to produce electricity．In the long run, electricity from large wind farms in remote areas might be used to make hydrogen gas from water during periods when there is less than peak demand for electricity．The hydrogen gas could then be fed into a storage system and used to generate electricity when additional or backup power is needed.
D) Wind power is most economical in areas with steady winds．In areas where the wind dies down, backup electricity from a utility company or from an energy storage system becomes necessary．Backup power could also be provided by linking wind farms with a solar cell, with conventional or pumped-storage hydropower, or with efficient natural-gas-burning turbines．Some drawbacks to wind farms include visual pollution and noise, although these can be overcome by improving their design and locating them in isolated areas.
E ) Large wind farms might also interfere with the flight patterns of migratory birds in certain areas, and they have killed large birds of prey (especially hawks, falcons, and eagles) that prefer to hunt along the same ridge lines that are ideal for wind turbines．The killing of birds of prey by wind turbines has pitted environmentalists who champion wildlife protection against environmentalists who promote renewable wind energy．Researchers are evaluating how serious this problem is and hope to find ways to eliminate or sharply reduce this problem．Some analysts also contend that the number of birds killed by wind turbines is dwarfed by birds killed by other human-related sources and by the potential loss of entire bird species from possible global warming．Recorded deaths of birds of prey and other birds in wind farms in
the United States currently amount to no more than 300 per year．By contrast, in the United States an estimated 97 million birds are killed each year when they collide with buildings made of plate glass,57 million are killed on highways each year; at least 3.8 million die annually from pollution and poisoning ; and millions of birds are electrocuted each year by transmission and distribution lines carrying power produced by nuclear and coal power plants.
F) The technology is in place for a major expansion of wind power worldwide．Wind power is a virtually unlimited source of energy at favorable sites, and even excluding environmentally sensitive areas, the global potential of wind power is much higher than the current world electricity use．In theory, Argentina,Canada, Chile, China, Russia, and the United Kingdom could use wind to meet all of their energy needs．Wind power experts project that by the middle of the twenty-first century wind power could supply more than 10 percent of the world's electricity and 10--25 percent of the electricity used in the United States.
G) Electrical phenomena have been studied since antiquity, though advances in the science were not made until the seventeenth and eighteenth centuries．Practical applications for electricity however remained few, and it would not be until the late nineteenth century that engineers were able to put it to industrial and residential use．The rapid expansion in electrical technology at this time transformed industry and society．Electricity's extraordinary versatility as a means of providing energy means it can be put to an almost limitless set of applications which include transport, heating, hghting, communications, and
computation．Electrical power is the backbone of modem industrial society.
H) The word electricity is from the New Latin electricus, "amber-like", coined in the year 1600 from the Greek ηλεκτρον (electron) meaning amber, because electrical effects were produced classically by
rubbing amber.
I) Long before any knowledge of electricity existed people were aware of shocks from electric fish．Ancient Egyptian texts dating from 2750 BC referred to these fish as the "Thunderer of the Nile", and described them as the "protectors" of all other fish.
J) Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians．Several ancient writers, such as Pliny the Elder and Scribonius Largus, attested to the numbing effect of electric shocks delivered by catfish and torpedo rays, and knew that such shocks could travel along conducting objects．Patients suffering from ailments such as gout or headache were directed
to touch electric fish in the hope that the powerful jolt might cure them.
K) Possibly the earliest and nearest approach to the discovery of the identity of lightning, and electricity from any other source, is to be attributed to the Arabs, who before the 15th century had the Arabic word for lightning (raaD．applied to the electric ray.
L) Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, could be rubbed with cat's fur to attract light objects like feathers.
M) Thales of Miletos made a series of observations on static electricity around 600 BC, from which he believed that friction rendered amber magnetic, in contrast to minerals such as magnetite, which needed no rubbing.
N) Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity.
O) According to a controversial theory, the Parthians may have had knowledge of electroplating, based on the 1936 discovery of the Baghdad Battery, which resembles a galvanic cell, though it is uncertain whether the artifact was electrical in nature.
In 1994 there were nearly 20,000 wind turbines worldwide, most grouped in clusters called wind farms that collectively produced 3,000 megawatts of electricity.