Nowadays people are putting our water supply in danger, because they use too much water or throw rubbish into the river. You may wonder how paving(铺砌) a road can lead to less usable fresh water. A major part of thewaterweuse every day is groundwater. Groundwater does not come from lakes or rivers. It comes from underground. The more roads and parking lots we pave，the less water can flow into the ground to become groundwater.

    Human activity is not responsible for all water shortages(短缺). Drier climates are of course more likely to have droughts(干旱) than areas with morerainfall，but in any case, good management can help to make sure there is enough water to meet our basic needs.

    Thinking about the way we use water every day can make a big difference，too. In the United States，a family of four can use 1.5 tons of water a day! This shows how much we depend on water to live，but there's a lot we can do to lower the number.

    You can take steps to save water in your home. To start with，use the same glass for your drinking water all day. Wash it only once a day. Run your dishwasher (洗碗机)only when it is full. Help your parents fix any leaks in your home. You can even help to keep our water supply clean by recycling batteries instead of throwing them away.

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    Dec.11 marked the 15th anniversary of China's entry into the World Trade Organization (WTO). On that day in 2001, China formally became a member of the WTO. Now the country has grown into the world's second-largest economy and the largest trading country, while millions of Chinese have been lifted out of poverty. And 15 years on, it's evident that being a WTO member has transformed the nation's everyday lives for the better.

    Imports are now a common sight in Chinese stores and supermarkets, while they were previously rarely seen on shelves. The Chinese now have access to many imports varying from luxury goods like high-end cars and famous brand watches, to daily necessities. China's WTO membership has also made imports less expensive for the Chinese public.

    For instance, since 2005, no tariffs (关税) have been imposed (施加) on Chinese imports of digital cameras and other devices.

    Our education industry has also benefited from China's WTO membership. Many top global universities have joined forces with Chinese ones to establish cooperative education institutions, bringing foreign teaching concepts to Chinese students. For example, New York University Shanghai was jointly founded by New York University and East China Normal University. In addition, an increasing number of Chinese students are furthering their studies abroad, while many foreign students are coming to China to carry out their higher education. According to the Ministry of Education, 523,700 students studied overseas last year, and the number is expected to keep growing this year.

    China's WTO entry has brought benefit not only to the country's people, but also for the rest of the world.

    If your dog looks pleased to see you—it is probably because it loves the particular way you smell.

    The scent (气味)of a familiar human apparently lingers like perfumein the animal's brain—where it causes an instinctive emotional response, research reveals.

    Our scent acts on a part of the canine (犬科的) brain associated with reward and the strongest reactions are produced by humans that pets know best, say scientists in America.

    Gregory Bern, of Emory University in Atlanta, said, “While we might expect that dogs should be highly tuned to the smell of other dogs, it seems that the 'reward response' is reserved for their humans. When humans smell the perfume of someone they love, they may have an immediate, emotional reaction that's not necessarily cognitive (认识的). So is it in dogs. But since dogs have a more sensitive smell than humans, their responses would likely be even more powerful than the ones we might have. In our experiment, however, the owners of the dog were not physically present. The canine brain responses were being caused by something distant in space and time. It shows that dogs' brains have these mental representations of us that persist when we're not there.”

    The experiment involved 12 dogs of various kinds by brain scans while five different scents were placed in front of them. The scent samples (样本)came from the subject (接受试险者) itself, a dog the subject had never met, a dog living in the subject's household. The familiar human scent samples were taken from someone else from the house other than the handlers during the experiment, so that none of the scent donors were physically present.

    The results showed all five scents gained a similar response in parts of the dogs brains involved in detecting smells. Responses were significantly stronger for the scent of familiar humans, followed by that of familiar dogs. The findings showed dogs reacted strongest to the scent of familiar humans even when they were not there. Pets trained as help or therapy dogs showed greater brain activity than the other dogs in the test.

    Researchers say the findings could improve the way to select animals helping wounded old soldiers or disabled people.

    Have you heard of the following people? Maybe yes, maybe no. But they may be an inspiration for you.

    The Tree Lady

    Kate Sessions was an American botanist and landscape architect closely associated with San Diego, California. After becoming the first woman to graduate from the University of California, Berkeley, she took a job as a teacher far south in the dry desert town of San Diego. Kate decided that San Diego needed trees more than anything else. Therefore, this young woman single-handedly started a movement transforming the town into the leafy, garden-filled place as it is today.

    The Snowflake(雪花) Man

    Wilson Bentley is one of the first known photographers of snowflakes. His enthusiasm for taking photos began from his boyhood and was often misunderstood in his time, but his determination revealed two important truths: no two snowflakes are alike; and each is surprisingly beautiful. In 1931, he worked with William J. Humphreys of the U.S. Weather Bureau to publish Snow Crystals, a book containing 2500 photographs.

    The Father of His Country

    By the late 1760s, George Washington had experienced firsthand the effects of rising taxes imposed (征收) on American colonists by the British, and came to believe that it was in the best interests of the colonists to declare independence from England. During the American War of Independence, he led the colonial forces to victory. In 1878, he was elected president of the Convention that wrote the U.S. Constitution. Two years later, Washington became American's first president. His retirement from office after two terms established a tradition that lasted until 1940, when Franklin Delano Roosevelt won a third term. The 22^nd Amendment (1951) now limits the president to two elected terms.

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    At 17, Mark Merwitzer might be Florida's youngest lobbyist (游说者). The Miami high school junior appeals to authorities to keep drivers from texting behind the wheel.

    Over the past year, the teen has met with county officials and state legislators (立法者)to argue that the police should be able to pull drivers over just for using their phones. Efforts in past years have struggled to advance, but recently, the bill got full support from the Senate Transportation Committee (参议院交通委员会).

    Like many US people, Merwitzer has seen countless drivers texting behind the wheel. But last spring, while he was riding in the passenger seat of a vehicle, he saw drivers using smartphones in almost every car. A few drivers even appeared to lose control of their cars as they sped along. It dawned on (突然想到) Merwitzer that no one was doing anything to fix the problem.

    We need to teach drivers how to properly and safely use technology behind the wheel which is not using it at all,” said Merwitzer.

    For the 17-year-old teenager, advocating a new state law has been a crazy experience.

    In order to carry out his plan，he put his focus on drumming up (争取)local support by starting an online petition (请愿)and speaking to village councils,

    Merwitzer said the first time he spoke at a council meeting “was a complete stutter fest (口吃表演)，” but he quickly adapted to it.

    “It really creates some standards that help everybody realize the importance of keeping their eyes on the road,” said Miami-Dade Commissioner (专员)Levine Cava.

The commissioner has been so impressed with Merwitzer's understanding of the political process. “He really learned very quickly how to be an effective citizen lobbyist,” she said.

    So far, opposition to the bill has come mainly from police departments. Some are worried about the possibility of lawsuits (诉讼)if officers are accused of racially profiling (按种族形象定性) drivers when accusing them of texting and driving，Merwitzer said. The bill also has critics in the House, where lawmakers have yet to make plans for a hearing.

    Merwitzer said he would one day like to be a state legislator, but in the meantime he has a few short-term goals, like finishing school and going to college. Once the legislative session (期间) is over, Merwitzer plans to turn his attention to another local problem: public transportation. “I'd like to focus on that，” Merwitzer said. “It seems like it's a giant mess,”