Unit3课后两篇课文挖空训练高中英语人教版选择性必修第三册.docx

SMALL WASTE, BIG PROBLEMMany of us might not give _1_ second thought to _2_(drop) a small piece of litter. After all, if it is so small, it cannot possibly be that harmful, can it? In today's world, the answer is certainly "Yes it can!" With the growing use of plastic bags and the rising number of smokers, there is more litter _3_(produce) than ever before. _4_ cigarette butts are small, they are bad for the environment. Worldwide, about 4.3 trillion cigarette butts _5_(litter) every year. As well as spoiling the beauty of the environment, they contain toxic chemicals. These find their way into the water supply _6_ they affect water quality and endanger plants and animals. Cigarette butts can take up to 25 years to break down, and the toxic chemicals add up to a large amount with so many _7_(litter). So, if people want to smoke, they should dispose _8_ the butts properly in a rubbish bin. Plastic bags are another common form of litter that is dangerous to the environment. They easily _9_(blow) by wind and float in water, so they can travel long distances. They find their way to rivers, parks, _10_(beach), and oceans, _11_(kill) many birds, mammals, fish, and sea animals each year worldwide. They can last for hundreds of years in the environment. We should not let plastic bags become litter. We should use fewer plastic bags, and reuse and recycle what we have already used.A CLEAN, GREEN ENERGY FUTUREThe world's energy needs are growing every year. As countries develop and their populations grow, the demand _1_ the energy to support them increases. Until now, this growth _2_(rely) heavily on the use of fossil fuels (coal, oil, and gas). Although their use has been essential so far, _3_(rely) on them has led to pollution problems, and perhaps the greatest future challenge for mankind, climate change. _4_(thankful), many countries are making the important change from fossil fuels to clean, green, and renewable sources of energy. Fossil fuels produce emissions, such as carbon dioxide, _5_ contribute to the greenhouse effect and the global climate. They are also "finite" sources, which means there is a _6_(limit) supply of them. Once a source _7_(use) up, another must be found, and finding new sources becomes more difficult and expensive over time. With no emissions or waste, renewable energy sources cause limited damage _8_ the environment. They are renewable because they can be naturally replaced and can therefore be consumed _9_ the risk of using them up. Here are the main types of renewable energy, _10_ facts and examples from around the world. HydropowerThe power of water turns turbines _11_ produce electricity. Since ancient times, watermills _12_(use) for many things, from grinding wheat to _13_(saw) timber. Countries such as Paraguay and Norway already produce all or most of their energy from hydropower. Most of the renewable energy in China comes from hydropower plants, such as the Three Gorges Dam, the world's _14_(large)t power station. SolarSolar panels turn heat from the sun's rays into electricity, and solar heaters use that energy to heat water directly. This is the fastest growing renewable energy source, as the cost of the technology _15_(fall). Germany has the highest solar capacity in the world, _16_ China is the world's largest market and the largest producer of solar technology.WindTall turbines are turned by the wind to produce electricity. Wind "farms" are built on land, or offshore, to take advantage _17_ more frequent and powerful winds at sea. The world's largest wind farm is the London Array. It has 175 wind turbines and is 20 km _18_ the coast of England. Researchers think China could meet all her electricity demands from wind by 2030. Wind farms in provinces such as Gansu have an _19_(end) wind supply. GeothermalThis has been a natural source of energy for thousands of years. Today, heat from below the earth's surface heats water into steam that turns turbines _20_(generate) electricity. The USA has the largest capacity, with over 80% _21_(generate) in California. The Yangbajing Power Plant is the largest geothermal plant in China. Biofuel This is material from biological sources (such as corn or grain) or waste products that _22_(use) to produce energy. It is used in generators for electricity, or in cars and other machines. Brazil has produced and used biofuel made from sugar cane for 40 years. China is the world's third _23_(large) producer of biofuel.So, what are the pros and cons of _24_(renew) energy?The strongest "pro" is that it is clean, _25_(produce) almost no pollution. Resources are abundant and free and cannot be used up. Projects, once set up, require less to maintain. They are ideal _26_ a small scale; one can have solar panels on the roof, but not a coal power station in the kitchen! It is also better for energy security. _27_(get) resources from within the country means less reliance _28_ resources from abroad, and less risk from political or _29_(economy) changes.There are also some "cons". With no wind or sun, there may be no power. Projects are built in places where resources are abundant, _30_ often far away from the cities where power is needed. Solar projects are expensive to set up. Hydroelectric projects can cause problems with _31_(flood) when they change the natural flow of rivers. Biofuel projects use up land, _32_ could be used for growing food. Can renewables really be the future of energy? Our modern world has been built on fossil fuels, _33_ it is hard to change quickly. However, the use of renewable energy is growing in China and around the world. _34_(give) the problems of climate change, there is little doubt _35_ they will continue to grow. _36_ extracting fossil fuels is becoming more difficult and expensive, the cost of renewable energy is falling. New battery technology, for example, solves the problem of bringing electricity from distant sources to cities. Along with our _37_(be) more aware of our energy _38_(consume) and waste, a clean, green energy future is possible and necessary. 4 / 4