更多"A Hydro power Introduction "的相关试题:
[填空题]A
Hydro power
Introduction
We have used running water as an energy source for thousands of years, mainly to grind com.
The first house in the world to be lit by hydroelectricity was Cragside House, in Northumberland, England, in 1878. In 1882 on the Fox River, in the USA, hydroelectricity produced enough power to light two paper mills and a house.
Nowadays there are many hydro-electric power stations, providing around 20% of the world’s electricity. The name comes from“hydro”, the Greek word for water.
How it works
A dam is built to trap water, usually in a valley where there is an existing lake.
Water is allowed to flow through tunnels in the dam, to turn turbines and thus drive generators.
Advantages
Once the dam is built, the energy is virtually free.
No waste or pollution produced.
Much more reliable than wind, so
[单项选择]Today almost 70% of the electrical power we use comes from power plants that use fossil fuels (矿物燃料) to make electricity. Fossil fuels, such as oil, coal, and natural gas, are burned to make electricity. Burning fossil fuels releases pollution and carbon dioxide gas (CO2) into the air. The more fossil fuels we burn, the warmer the air around Earth gets. So building fossil fuel plans is not always the best answer.
Actually, there are other ways to make electricity without burning fossil fuels. People have been using the power of wind for centuries. Wind power won’t solve all our energy problems, but it can help meet some of the demands in certain places. Since the late 1800s, scientists have been working to turn the sun’s energy into electricity by using solar cells (太阳能电池). The problem is, solar cells are very expensive. Another way to make electricity is to use nuclear energy. It has been used for more than 50 years. Today about 10 percent of all the electricity used in the U.S.A
A. The Importance of Electricity
B. The Pollution of Making Electricity from Fossil Fuels
C. The Advantage of Using Nuclear Energy
D. Means of Making Electrical Power
[填空题]The member states of UN have the power to use force against other state to deal with the problems in international relations.
[填空题]We might use more of our native memory power if we learnt how to use it at school,
[单项选择]We hadn’t expected a power cut so we were astonished when the whole house was ______ into darkness.
A. dived
B. plunged
C. drowned
D. dropped
[单项选择]
For years we have believed we were either healthy or sick. (55) , during the mid-90s, scientists developed a new concept called "sub-health", a status (56) health and illness. The concept of sub-health has become (57) because it has helped to explain many health problems. (58) one study, only 5. 6% of people in the overall population are actually sick, (59) the subhealthy group consists of about 60%, and the (60) population is considered healthy. (61) of one’s sub-health will help one to be alert to the underlying disease and remain healthy. Sub-health is a state in which the body is (62) turning from health to illness or from illness to health. Our bodies are actively (63) the conditions of health, sub-health and disease. Factors (64) aging, internal or external toxicity (毒性), and body or mind exhaustion may cause sub-health, but taking good care of the body can change a sub-
A. remaining
B. retaining
C. relating
D. reserving
