3 . The connection between people and plants has long been the subject of scientific research. Recent studies have found positive effects. A study conducted in Youngstown，Ohio，for example, discovered that greener areas of the city experienced less crime. In another，employees were shown to be 15% more productive when their workplaces were decorated with houseplants.

The engineers at the Massachusetts Institute of Technology(MIT)have taken it a step further changing the actual composition of plants in order to get them to perform diverse，even unusual functions. These include plants that have sensors printed onto their leaves to show when they’re short of water and a plant that can detect harmful chemicals in groundwater. ＂We’re thinking about how we can engineer plants to replace functions of the things that we use every day,＂explained Michael Strano, a professor of chemical engineering at MIT.

One of his latest projects has been to make plants glow(发光)in experiments using some common vegetables. Strano’s team found that they could create a faint light for three-and-a-half hours. The light，about one-thousandth of the amount needed to read by，is just a start. The technology, Strano said, could one day be used to light the rooms or even to turn trees into self-powered street lamps.

In the future，the team hopes to develop a version of the technology that can be sprayed onto plant leaves in a one-off treatment that would last the plant’s lifetime. The engineers are also trying to develop an on and off＂switch＂where the glow would fade when exposed to daylight.

Lighting accounts for about 7% of the total electricity consumed in the US. Since lighting is often far removed from the power source(电源)-such as the distance from a power plant to street lamps on a remote highway-a lot of energy is lost during transmission(传输).Glowing plants could reduce this distance and therefore help save energy.

4 . Molai grew up in a tiny village in India. The village lay near some wetlands which became his second___________. He learned the value and beauty of _________ there from a very young age.

When he was 16, Molai began to notice something _________ happening around his home. A flood had hit the area earlier that year and the _________ it caused had driven away a number of birds. _________, the number of snakes had declined as well. He _________ that it was because there weren’t enough trees to protect them from the _________. The solution, of course, was to plant trees so the animals could seek _________ during the daytime. He turned to the _________ department for help but was told that nothing would grow there. However, Molai went looking on his own and __________a nearby island where he began to plant trees.

________ young plants in the dry season was ____________for a lone boy. Molai built at the __________ of each sapling(幼树)a bamboo platform, where he placed earthen pots with small holes to____________ rainwater. The water would then drip(滴落)on the plants below.

Molai __________ to plant trees for the next 37 years. His efforts have resulted in 1,360 acres of naturally-grown land that has become home to many plants and animals.

The polar bear is found in the Arctic Circle and some big land masses as far south as Newfoundland. While they are rare north of 88°, there is evidence     1     they range all the way across the Arctic, and as far south as James Bay in Canada. It is difficult to figure out a global population of polar bears as much of the range has been     2    (poor) studied; however, biologists calculate that there are about 20,000-25,000 polar bears worldwide.

Modern methods     3     tracking polar bear populations have been employed only since the mid-1980s, and are expensive     4    (perform) consistently over a large area. In recent years some Inuit people in Nunavut     5    (report) increases in bear sightings around human settlements, leading to a     6    (believe) that populations are increasing. Scientists have responded by     7    (note) that hungry bears may be congregating(聚集) around human settlements, leading to the illusion(错觉) that populations are     8    (high) than they actually are. Of     9     nineteen recognized polar bear subpopulations, three are declining, six     10    (be) stable, one is increasing, and nine lack enough data.

6 . Every year about 40,000 people attempt to climb Kilimanjaro, the highest mountain in Africa. They _______ with them lots of waste. The _______ might damage the beauty of the place. The glaciers(冰川) are disappearing, changing the _______ of Kilimanjaro.

Hearing these stories, I’m _______ about the place — other destinations are described as “purer” natural experiences.

However, I soon _______ that much has changed since the days of disturbing reports of _______ among tons of rubbish. I find a _______ mountain, with toilets at camps and along the paths. The environmental challenges are _______ but the efforts made by the Tanzania National Park Authority seem to be _______.

The best of a Kilimanjaro ________, in my opinion, isn’t reaching the top. Mountains are ________ as spiritual places by many cultures. This ________ is especially evident on Kilimanjaro as ________ go through five ecosystems(生态系统) in the space of a few kilometers. At the base is a rainforest. It ends abruptly at 3, 000 meters, ________ lands of low growing plants. Further up, the weather ________ — low clouds envelope the mountainsides, which are covered with thick grass. I ________ twelve shades of green from where I stand. Above 4, 000 meters is the highland ________: gravel(砾石), stones and rocks. ________ you climb into an arctic-like zone with ________ snow and the glaciers that may soon disappear.

Does Kilimanjaro ________ its reputation as a crowded mountain with lines of tourists ruining the atmosphere of peace? I found the opposite to be true.

7 . When you were trying to figure out what to buy for the environmentalist on your holiday list, fur probably didn’t cross your mind. But some ecologists and fashion (时装)enthusiasts are trying to bring back the market for fur made from nutria(海狸鼠).

Unusual fashion shows in New Orleans and Brooklyn have showcased nutria fur made into clothes in different styles. “It sounds crazy to talk about guilt-free fur-unless you understand that the nutria are destroying vast wetlands every year”, says Cree McCree, project director of Righteous Fur.

Scientists in Louisiana were so concerned that they decided to pay hunters $5 a tail. Some of the fur ends up in the fashion shows like the one in Brooklyn last month.

Nutria were brought there from Argentina by fur farmers and let go into the wild. “The ecosystem down there can’t handle this non-native species(物种).It’s destroying the environment. It’s them or us.” says Michael Massimi, an expert in this field.

The fur trade kept nutria in check for decades，but when the market for nutria collapsed in the late 1980s，the cat-sized animals multiplied like crazy.

Biologist Edmond Mouton runs the nutria control program for Louisiana. He says it’s not easy to convince people that nutria fur is green, but he has no doubt about it. Hunters bring in more than 300,000 nutria tails a year, so part of Mouton’s job these days is trying to promote fur.

Then there’s Righteous Fur and its unusual fashion. Model Paige Morgan says，”To give people a guilt-free option that they can wear without someone throwing paint on them-I think that’s going to be a massive thing, at least here in New York.” Designer Jennifer Anderson admits it took her a while to come around to the opinion that using nutria fur for her creations is morally acceptable. She is trying to come up with a label to attach to nutria fashions to show it is eco-friendly.

Diets have changed in China — and so too has its top crop. Since 2011, the country     1    （grow）more corn than rice. Corn production has jumped nearly 125 percent over     2     past 25 years, while rice has increased only 7 percent.

A taste for meat is     3     (actual) behind the change: An important part of its corn is used to feed chickens, pigs, and cattle. Another reason for corn's rise: The government encourages farmers to grow corn instead of rice     4     (improve) water quality. Corn uses less water     5     rice and creates less fertilizer(化肥) runoff. This switch has decreased     6     (pollute) in the country's major lakes and reservoirs and made drinking water safer for people.

According to the World Bank, China accounts for about 30 percent of total     7     (globe)fertilizer consumption. The Chinese Ministry of Agriculture finds that between 2005—when the government     8     (start) a soil-testing program     9     gives specific fertilizer recommendations to farmers - and 2011, fertilizer use dropped by 7.7 million tons. That prevented the emission(排放) of 51.8 million tons of carbon dioxide. China's approach to protecting its environment while     10     (feed) its citizens "offers useful lessons for agriculture and food policymakers worldwide." says the bank's Juergen Voegele.