2 . In the United States alone,over 100 million cell-phones are thrown away each year.Cell-phones are part of a growing mountain of electronic waste like computers and personal digital assistants.The electronic waste stream is increasing three times taster than traditional garbage as a whole.

Electronic devices contain valuable metals such as gold and silver.A Swiss study reported that while the weight of electronic goods represented by precious metals was relatively small in comparison to total waste,the concentration（含量）of gold and other precious metals was higher in So-called e-waste than in naturally occurring minerals.

Electronic wastes also contain many poisonous metals.Even when the machines are recycled and the harmful metals removed,the recycling process often is carried out in poor countries,in practically uncontrolled ways which allow many poisonous substances to escape into the environment.

Creating products out of raw materials creates much more waste material,up to 100 times more,than the material contained in the finished products.Consider again the cell-phone,and imagine the mines that produced those metals,the factories needed to make the box and packaging（包装）it came in.Many wastes produced in the producing process are harmful as well.

The U.S Environmental Protection Agency notes that most waste is dangerous in that"the production, distribution,and use of products-as well as management of the resulting waste-all result in greenhouse gas release." Individuals can reduce their contribution by creating less waste at the start-for instance,buying reusable products and recycling.

In many countries the concept of extended producer responsibility is being considered or has been put in place as an incentive（动机）for reducing waste.If producers are required to take back packaging they use to sell their products,would they reduce the packaging in the first place?

Governments' incentive to require producers to take responsibility for the packaging they produce is usually based on money.Why,they ask,should cities or towns be responsible for paying to deal with the bubble wrap（气泡垫）that encased your television?

From the governments' point of view,a primary goal of laws requiring extended producer responsibility is to transfer both the costs and the physical responsibility of waste management from the government and tax-payers back to the producers.

Imagine living on the edge of a vast desert, which is moving quietly closer to your village every day and covering your fields. The desert is on the move. This is called desertification.

Desertification occurs in regions close to an already existing desert. It generally arises from two related causes. The first is over-use of water in the area. There is not enough water in any case, and if it is not carefully used, disaster can follow. As time goes on, water shortages make farming more and more difficult. In some places, locals can remember local lakes and marshes which were once the homes for all kinds of fish and birds. They have been completely buried by the sand now. Farmers leave the land, and fields are replaced by deserts.

The second cause is misuse or over-use of the land. This means that the wrong crops are planted and need more water than is available. Ploughing large fields and removing bushes and trees means that the wind will blow away the soil. Once the soil is lost, it is hard to replace, and if there is rain, it has nowhere to go, and brings no benefit.

It is not only the farmers and villagers who suffer. Every spring, the skies over some of eastern cities, thousands of kilometers away from the deserts, can be darkened by sandstorms. Dust from deserts can have a great effect on weather systems. While desertification is perhaps being partly caused by global warming, these sandstorms can make global warming worse by adding to what is known as the greenhouse effect.

What can be done to slow down or stop the process of desertification? A great deal of work is already under way. Obviously first steps are to find new water sources. Tree planting can help, by providing barriers between desert and rich field. Some types of grass also hold the soil together, and stop the wind taking it. Without these efforts, it will be harder and harder to stop the world’s deserts in their tracks, and more and more farmers will give up and head for cities. The lesson to be learnt lies beneath the sand.

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4 . When prehistoric man arrived in new parts of the world, something strange happened to the large animals. They suddenly became extinct. Smaller species survived. The large, slow-growing animals were easy game, and were quickly hunted to extinction. Now something similar could be happening in the oceans.

That the seas are being overfished has been known for years. What researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing. They have looked at half a century of data from fisheries around the world. Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time. According to their latest paper published in Nature, the biomass of large predators (animals that kill and eat other animals) in a new fishery is reduced on average by 80% within 15 years of the start of exploitation. In some long-fished areas, it has halved again since then.

Dr. Worm acknowledges that the figures are conservative. One reason for this is that fishing technology has improved. Today's vessels (船)can find their prey using satellites and sonar, which were not available 50 years ago. That means a higher proportion of what is in the sea is being caught, so the real difference between present and past is likely to be worse than the one recorded by changes in catch sizes. In the early days, too, longlines (多钩长线) would have been more filled with fish. Some individuals would therefore not have been caught, since no baited hooks (带饵钩)would have been available to trap them, leading to an underestimate of fish stocks in the past. Furthermore, in the early days of longline fishing, a lot of fish were lost to sharks after they had been hooked. That is no longer a problem, because there are fewer sharks around now。

Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the data support an idea current among marine biologists, that of the “shifting baseline". The idea is that people have failed to detect the massive changes which have happened in the ocean because they have been looking back only a relatively short time into the past. That matters because theory suggests that the maximum sustainable yield （产量）that can be cropped from a fishery comes when the biomass of a target species is about 50% of its original levels。. Most fisheries are well below that, which is a bad way to do business.

5 . How Saving Wildlife Benefits Humans

It’s no secret that we’ve lost an overwhelming number of species within that last four decades. These species have all but _____ due to overpopulation, deforestation, consumer culture, climate change, animal exploitation, and other harming sources — all brought about by mankind.

One of the first great rules of terrestrial (陆地的) biology is “no species is forever.” _____, this rapid loss of species today is estimated to be between1,000and 10,000 times higher   than the natural extinction rate. As increasingly accepted theories have argued, we are now in the midst of the sixth great _____.

The Earth consists of plants, animals, water,   land, the atmosphere, and humans.   Biodiversity (生物多样性) _____ the health of the planet and has a great impact on all our lives. Reduced biodiversity means a future where food supplies are vulnerable (易受攻击的) to pests and disease, and fresh water is   in short supply. If biodiversity _____ impacts   our lives in such big   ways, then our conservation (环保) efforts don’t just benefit the environment, they benefit us, too.

One convincing benefit that comes from wildlife conservation efforts is that it ensures food _____. Wildlife conservation promotes agricultural biodiversity, which plays an important role in building a secure and healthy food system. When agricultural biodiversity is _____ and land   is cleared for agriculture, extensive habitat loss takes place, as well as undocumented loss of species and massive soil erosion (侵蚀).

Another benefit that comes from wildlife conservation is that these _____ protect human health. Conservation International reportsthat “more than 50 percent of modern medicines and more than 90 percent of traditional medicines   come from wild plants   and animals.” _____,   a     world that promotes healthy ecosystems and biodiversity provides crucial buffers (缓冲) between disease and humans. A number of studies have _____ reduced diversity among mammal (哺乳动物 ) species and overall decreases in biodiversity to an increase in the transmission ( 传 播 ) of animal-born diseases to humans.

Perhaps the most convincing benefit that comes from wildlife conservation is that it provides us with _____ whether it be economically or socially. Increasing biodiversity and   healthy ecosystems improve agricultural productivity, thereby allowing farms to become more _____. Healthy ecosystems that are home to unique species _____ tourists from around the world, which helps the local economy and invites in a new fusion of investment.

Our unsustainable, unconscious, self-interested relationship with the environment has led us into an extremely destructible world. If we do not take action and _____ changing our ways, we     are at risk of losing more vital and _____ ecosystems and biodiversity,   or at least until the sixth   great extinction claims one final species: our own.

8 . Now elsewhere in the world, Iceland may be spoken of, somewhat breathlessly, as western Europe's last pristine wilderness. But the truth is, once you're off the ______ track of the low-lying coastal areas where everyone lives, the roads are few, and they're all bad, ______ Iceland's natural wonders have been out of reach and unknown even to its own ________For them the land has always just been there, something that had to be dealt with and, if possible, _______—the mind-set being one of land as commodity rather than land as, well, priceless art on the scale of the " Mona Lisa".

When the opportunity arose in 2003 for the national power company to enter into a 40-year ______ with the American aluminum company Alcoa to supply hydroelectric power for a new smelter （冶炼厂）, those who had been dreaming of something like this for decades ______ the opportunity. For a long time, life here had meant little more than a hut, dark all winter, cold, no hope, children dying left and right, plagues, starvation, volcanoes erupting and destroying all vegetation and livestock, all spirit— a world ______ almost entirely around the welfare of one's sheep and, later, on how good the cod catch was. In the outlying regions, it still largely does.

Ostensibly, the Alcoa project was intended to save one of these dying regions— the remote and sparsely populated east— where the way of life had steadily ______ to a point of desperation and gloom. After fishing quotas (定额) were ______ in the early 1980s to protect fish stocks, many individual boat owners sold their allotments or gave them away, fishing rights ended up mostly in the hands of a few companies and small fishermen were virtually ______. Technological advances drained away even more jobs previously done by human hands, and the people were seeing everything they had worked for all their lives turn out to be ______ and their children move away. With the old way of life doomed, aluminum projects like this one had come to be perceived, wisely or not, as a last chance. "Smelter or death."

The contract with Alcoa would infuse the region with foreign ______, an estimated 400 jobs, and spin-off service industries. It also was a way for Iceland to develop expertise that ______ could be sold to the rest of the world and ______ an economy historically dependent on fish. “We have to live,” Halldor Asgrimsson said. Halldor, a former prime minister and longtime member of parliament from the region, was a driving ______ behind the project. “We have a right to live.”

Every autumn, millions of the North American monarch butterflies begin a long and difficult journey. Somehow they manage to travel around 4,000 kilometres south and find their way to California or Mexico. However, until recently no one     1     (know) how they did this.

A team of scientists     2     (lead) by Professor Eli Shlizerman has now found the answer. They have found out that the monarch is able to tell the time of day. It uses its eyes     3     (measure) the position of the sun. These two pieces of information allow the butterfly     4     (determine) the way to go. Finally, it manages to reach the places where it will spend the winter.

    5     (sad), human activity is the main reason     6     the number of monarch butterflies is falling. In many of the places where the butterfly can be found, people are destroying the     7     (nature) environment. They cut     8     trees and use chemicals that kill the plants that monarch caterpillars eat.

The research on the monarch’s behaviour has however led to a greater     9     (aware) of this creature. People have been working together to record its migration and make sure that there are enough plants for it to feed on. If this works, there may come a time when     10     number of monarch butterflies increases once again.