D

      The meaning of silence varies among cultural groups. Silences may be thoughtful, or they may be empty when a person has nothing to say. A silence in a conversation may also show stubbornness, or worry. Silence may be viewed by some cultural groups as extremely uncomfortable; therefore attempts may be made to fill every gap(间隙)with conversation. Persons in other cultural groups value silence and view it as necessary for understanding a person's needs.

        Many Native Americans value silence and feel it is a basic part of communicating among people, just as some traditional Chinese and Thai persons do. Therefore, when a person from one of these cultures is speaking and suddenly stops, what maybe implied(暗示) is that the person wants the listener to consider what has been said before continuing. In these cultures, silence is a call for reflection.

        Other cultures may use silence in other ways, particularly when dealing with conflicts among people or in relationships of people with different amounts of power. For example, Russian, French, and Spanish persons may use silence to show agreement between parties about the topic under discussion. However, Mexicans may use silence when instructions are given by a person in authority rather than be rude to that person by arguing with him or her. In still another use, persons in Asian cultures may view silence as a sign of respect, particularly to an elder or a person in authority.

Nurses and other care-givers need to be aware of the possible meanings of silence when they come across the personal anxiety their patients may be experiencing. Nurses should recognize their own personal and cultural construction of silence so that a patient's silence is not interrupted too early or allowed to go on unnecessarily. A nurse who understands the healing(治愈) value of silence can use this understanding to assist in the care of patients from their own and from other cultures.

    Houses fall down. Trees fall over. Large holes form in the ground. Could Alaska be sinking? That's what some villagers in Alaska have been asking themselves recently and scientists think they know why. Warmer temperatures may be causing Alaska's frozen ground to thaw (解冻).

    About 85 percent of Alaska's land surface has permafrost (永久冻结带). Permafrost supports the ground above it—including trees, houses, and roads. But why is the permafrost thawing?

    Some scientists say that human-caused pollution is leading to global warming. And most scientists agree that Alaska has been getting warmer. They say that the warmer temperature is causing permafrost to thaw in some areas. The thawing permafrost can cause problems for people, plants, and animals.

    The collapsing (倒塌) is a problem in the villages in Alaska which are built on permafrost, and some of them may have to move to safer ground, where there is no permafrost.

    The Alaskan town of Glennallen saw its old post office collapse. And, according to James Walters, a permafrost expert at the University of Northern Iowa, house-moving companies have been very busy.

    “Melting permafrost can also destroy trees and forests,” Walters said. “When holes in the ground form, trees fall into them and die. This could turn a forest into a swamp (沼泽), and animals which need the forests will have to move elsewhere.”

    “The melting could cause severe problems.” Walters says, “This could take hundreds of years, but in the end Alaska will look quite different from what it looks like now.”

    The following are introductions to some programs that BBC I will show on TV.

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。

    A new study warns that about thirty percent of the world's people may not have enough water by the year 2025.

    A private American organization called Population Action International did the new study. It says more than 335 million people lack enough water now. The people live in 28 countries. Most of the countries are in Africa or the Middle East.

    P-A-I researcher Robert Engelman says by the year 2025, about 3,000 million people may lack water. At least 18 more countries are expected to have severe water problems. The demand for water keeps increasing. Yet the amount of water on the earth stays the same.

    Mr. Engelman says the population in countries that lack water is growing faster than in other parts of the world. He says population growth in these countries will continue to increase.

    The report says lack of water in the future may result in several problems. It may increase health problems. Lack of water often means drinking water is not safe. Mr Engelman says there are problems all over the world because of diseases, such as cholera, which are carried in water. Lack of water may also result in more international conflict. Countries may have to compete for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan, and Iraq. And the report says lack of water would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.

    The Population Action International study gives several solutions to the water problem. One way, it says, is to find ways to use water for more than one purpose. Another way is to teach people to be careful not to waste water. A third way is to use less water of agriculture.

    The report also says long-term solutions to the water problem must include controls on population growth. It says countries cannot provide clean water unless they slow population growth by limiting the number of children people have.

Big Stuff

Do you know what is the tallest building in the world and where the tallest Ferris wheel is? Have you heard of the world's steepest roller coaster? Have you seen the biggest monster truck? Here are some of the most huge things on Earth.

A Towering Achievement

Burj Khalifa, a tower in Dubai, United Arab Emirates, is the world's tallest structure. The 162-story building, which opened in 2010, stands over 2,717 feet tall. Seen from above, the tower has a Y-shaped design. Its three tall, narrow wings are joined in the middle. Like the legs of a tripod （三脚架）, each wing is supported by the other two.

A Wheel Winner

About 15 miles from the world's tallest building stands the world's tallest Ferris wheel, Ain Dubai. Also called an observation wheel, Ain Dubai stands 820 feet tall. Each of the 48 cabins can carry 40 people for spectacular views of Dubai, United Arab Emirates. Before construction, support columns had to be driven 115 feet down through the earth to reach bedrock.

Extreme Ups and Downs

The world's tallest roller coaster is Kingda Ka at Six Flags Great Adventure. At 456 feet, the peak of the ride towers over nearby Jackson, New Jersey. A 500-foot-tall crane was needed to place the final section at the top. Like many weight-bearing structures, the tower makes use of the most stable geometric （几何的） shape, the triangle.

A Monster of a Truck

Designed and built by business owner Bob Chandler, Bigfoot 5 has held the record for the world's biggest monster truck since 

1986. Other trucks, including Bigfoot models, have been designed to perform better in competitions. But Bigfoot 5 still stands above the crowd, thanks to its 10-foot-tall tires. The tires were originally designed for equipment that drives on Alaska's snowy tundra.

In San Francisco,a large group of sea lions move themselves out of the bay waters and hang out on PIER 39, which is a popular tourist destination. According to dock（码头） officials, this is the most sea lions seen in the region in 15 years.

"Over 1,000 sea lions have been counted this week," PIER 39 harbor master Sheil a Chandor told many different medias. "The increase in sea lions is usually a good sign of their strong population and healthy living environment," said Adam Ratner, Director of Conservation Engagement at the Marine Mammal（海洋哺乳动物） Center in Sausalito, California.

"California sea lions are sentinels（哨兵） of the ocean," Ratner said. Their population to some extent reflects the health of the ocean. Therefore, seeing a large number of California sea lions is clearly a good thing.

For nearly 35 years, the animals have been a star attraction for visitors. That autumn in 1989, PIER 39 had just been repaired, but the ships had not yet been moved back. At that moment, the sea lions' unexpected arrival not only attracted fans but also created enemies. According to a website, some dock residents and workers were scared away by the strong and very unpleasant smell and noise of their new neighbors, while others saw these animals as a bright spot after the destructive Loma Prieta earthquake.

The officials sought help from the Marine Mammal Center to find a way to deal with sea lions. Ratner said that the final decision is to let the sea lions stay and coexist with humans. "The fact proves that this is really a good thing," he said. "This is just a proof of how we can truly work together and think about how we can share our coasts with marine mammals and other wildlife in a way that benefits all the parties involved."