The need to feed a growing population is putting much pressure on the world's supply of water. With 97% of the world's water too salty to be drunk or used in agriculture, the worldwide supply of water needs careful management, especially in agriculture. Although the idea of a water shortage(短缺)seems strange to someone fortunate enough to live in a high rainfall country, many of the world's agricultural industries experience constant water shortages.

    Although dams can be built to store water for agricultural use in dry areas and dry seasons, the costs of water redistribution(重新分配)are very high. Not only is there the cost of the engineering itself, but there is also an environmental cost to be considered. Where valleys(山谷)are flooded to create dams, houses are lost and wildlife homes destroyed. Besides, water may flow easily through pipes to fields, but it cannot be transported from one side of the world to the other. Each country must therefore rely on the management of its own water to supply its farming requirements. This is particularly troubling for countries with agricultural industries in areas dependent on irrigation. In Texas, farmers' overuse of irrigation water has resulted in a 25% reduction of the water stores.

    In the Central Valley area of southwestern USA, a huge water engineering project provided water for farming in dry valleys, but much of the water use has been poorly managed.

    Saudi Arabia's attempts to grow wheat in desert areas have seen the pumping of huge quantities of irrigation water from underground reserves. Because there is no rainfall in these areas, such reserves can only decrease, and it is believed that fifty years of pumping will see them run dry.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

    The U. S. Postal Service (USPS) is losing billions of dollars a year. The government company that delivers "small mail" is losing out to email and other types of electronic communication. First-class mail amount fell from a high point of 104 million pieces in 2000 to just 64 million pieces by 2014.

    Congress permits the 600.000-empIoyee USPS to hold a monopoly (垄断) over first-class and standard mail. The company pays no federal, state or local taxes; pays no vehicle fees; and is free from many regulations on other businesses. Despite these advantages, the USPS has lost $52 billion since 2007, and will continue losing money without major reforms.

    The problem is that Congress is preventing the USPS from reducing costs as its sales decline, and is blocking efforts to end Saturday service and close unneeded post office locations. USPS also has a costly union-dominated workforce that slows the introduction of new ideas or methods down. USPS workers earn significantly higher payment than comparable private-sector workers. The answer is to privatize the USPS and open postal markets to competition. With the rise of the Internet, the argument that mail is a natural monopoly that needs government protection is weaker than ever.

    Other countries facing declining letter amounts have made reforms Germany and the Netherlands privatized their national postal companies over a decade ago, and other European countries have followed suit. Britain floated shares of the Royal Mail on its stock exchange in 2013. Some countries, such us Sweden and New Zealand, have not privatized their national postal companies, but they have opened them up to competition.

    These reforms have driven efficiency improvements in all of these countries. Additional number of workers have been reduced, productivity has risen and consumers have benefited. Also, note that cost-cutting measures—such as closing tone post offices—are good for both the economy and the environment.

    Privatization and competition also encourage new changes. When the USPS monopoly over "extremely urgent" mail was stopped in 1979, we saw an explosion in efficient overnight private delivery by firms such as FedEx.

    The government needs to wake up to changing technology, study postal reforms abroad and let businessmen reinvent our out-of-date postal system.

    If you go into the forest with friends, stay with them. If you don't, you may get lost. If you get lost, this is what you should do. Sit down and stay where you are. Don't try to find your friends—let them find you. You can help them find you by staying in one place. There is another way to help your friends or other people to find you. You can shout or whistle(吹口哨) three times. Stop. Then shout or whistle three times again. Any signal given three times is a call for help.

    Keep up shouting or whistling. Always three times together. When people hear you, they will know that you are not just making a noise for fun. They will let you know that they have heard your signal. They will give you two shouts or two whistles. When a signal is given twice, it is an answer to a call for help.

    If you don't think that you will get help before night comes, try to make a little house with branches(树枝). Make yourself a bed with leaves and grass.

    When you need some water, you have to leave your little branch house to look for it. Don't just walk away. Pick off small branches and drop them as you walk in order to go back again easily. When you are lost, the most important thing to do is to stay in one place.

    Marathon fever is sweeping this country. In recent years, China's ever-growing passion for marathons has been triggered by its economic development and health-conscious middle class. A large number of marathon runners are white-collar workers, civil servants and business people that are keen on leading a healthy lifestyle. Government support, social participation and strong marketing by the sports industry have gradually led to the rapid development of the marathon industry, which is currently valued at 70 billion yuan ($10. 77 billion). Due to its large participation and nationwide media report, marathons are considered by local governments an important part of marketing their cities. Thus, many cities list unique routes across local scenic spots and historical attractions, not only to boost people's fitness, but also to promote local tourism.

    For many runners, marathons are a way of life." As we get older, the places and opportunities to meet new people decrease. I find that participating in marathons is a simple way to make friends," said Wu, who made many friends in the Xstop Running Community, a running club with 48, 000 members established by Xtep, one of the leading distributors of sports merchandise in China.

    "The sense of belonging and the mutual encouragement that exists within the running community are very attractive to many people. We easily befriend one another, since we have the same goal: to keep running and never stop," Wu said. Besides, a marathon can be a great way to explore new places. For a runner who also loves traveling, marathons are a solid choice. "Competing in an international marathon is a chance to experience a city or a country you've never visited before," said Meng, an experienced runner from north China's Tianjin Municipality, who often runs in London, New York and Melbourne.

    There's a unique perspective that people get running through the streets of a city, distinct ancient buildings or amazing natural settings, he explained, things that somehow just can't be seen by rushing in a car. In addition, during a race, streets are often closed off so you don't have to battle traffic.

    When your dream is to become a footballer, nothing should get in your way—even if you have no feet.

    Gabriel Muniz, an 11-year-old Brazil kid, was born without feet. Although his family thought he would have serious difficulties living a normal life, he started walking before he was one year old. His mother would go after him, expecting him to keep falling, but he never fell. It took him a while to make the jump from walking to playing football, but he did make it. And, in fact, there's nothing he loves more than playing football. In his school, the skillful youngster (年轻人) is not only the best player in his school team but also the captain of his gym team.

    He knows that his disability means he'll never be able to play for a professional (专业的) football team. So Gabriel is hoping that football will one day become a Paralympics (残疾人奥运会的) sport. He proved to everyone there he could go head to head with any other boy. Watching him play is unbelievable. He's fast and he's got a big bag of tricks—he's very skilled and he does everything he can to copy his hero, Messi so much that he is invited to go to Spain to meet his hero Messi and show his talent in the Barcelona Football Club.

    His coach says he is proving the disability only exists (存在) inside our heads.

Family Fun in Canadian Museum of Nature

    Bring the whole family to rediscover our fully redecorated museum.

    WHAT TO SEE AND DO

    Check out What's On for all the events, educational activities and HD movies happening during your visit. Care for birds, dive down into the depths at the helm (舵柄) of a research submersible(潜水器) or explore a cave… on the first floor. Don't miss our gallery play areas on the third floor when visiting with kids. By visiting here, your children will learn more about nature. Check out Our Exhibitions which present our special exhibitions and our galleries. Be sure to stop at our Nature Boutique on the second floor for a vast selection of games, books and nature-related souvenirs from 9:30 am until the museum closes for the day.

    HOURS, ADMISSION, SERVICES AND MORE

    The Canadian Museum of Nature provides a host of information, images and videos on our websites about nature, such as http://www.nature.ca/en/family-fun and http://www.expeditionarctic.ca/.The museum also participates in several social networks. Follow us on Facebook, YouTube, Instagram and Twitter.