Modem zoos are different from those built fifty years ago.At that time zoos were places where people could go to see animals from many parts of the world.The animals lived in cages with iron bars（栅栏）.Although the zoo keepers took good care of them,many of the animals did not feel comfortable,and they often fell ill.

    In modern zoos,people can see animals in more natural conditions.The animals are given more freedom in larger places so that they can live as they would in nature.Even the appearance of zoos has changed.Trees and grass grow in cages,and water flows through the places the animals live in.There are few bars;instead,there is often a deep ditch（沟）,filled with water,which surrounds a space where several sorts of animals live together as they would naturally.In an American zoo,the visitors can walk through a special huge cage that is filled with trees,some small animals and many birds,and large enough for the birds to live naturally.In a zoo in New York,with the use of special nights,people can observe certain animals that are active only at night,when most zoos are dosed.Some zoos have special places for visitors to watch animals that live in the desert or under water.

    Modern zoos not only show animals to visitors,but also keep and save rare animals.For this reason,fifty years from now,the grandchildren of today's visitors will still be able to enjoy watching these animals.

    Although Paris is often considered the city of romance, close to a million adult who call it home are single. Many single people say that France's capital is one of the most difficult places to meet people. The complaints of this lonely group have inspired a new phenomenon known as “supermarket dating.” At Galerie Lafayette Gourmet, singles can shop for more than just the items on their grocery list. They can look for someone who has blue eyes, brown hair, and is 1.8 meters tall, or whatever may be on their romantic shopping list.

    At this Paris location, single people of all ages can schedule their shopping for Thursday nights between 6:30 and 9:00 p.m. When they walk through the door, they pick up a purple basket to advise that they are looking for love. They try to arrive early because the baskets disappear quickly, and then they have to wait in line for their turn to wander the store aisles.

    With purple baskets in hand, shoppers can consider their romantic options while they pick out their groceries. When they are ready to pay, they can go to the checkout line for singles who want to chat.

    Most of the people who look for love in the supermarket are skeptical of Internet dating. They know that it is easy to embellish（美化）one's appearance or to lie about one's age over the Internet. The supermarket, on the other hand, is considered a safe and casual environment in which to meet a potential match. In addition, what one finds in another's grocery basket can say a thing or two about that person's character or intentions. Buying pet food can be a man's way of showing a potential match that he has a sensitive side. Women who fill their baskets with low-fat food show their healthy style of living. These days it's possible to find much more than food at a grocery store.

    Tourism wasn't as important as it is today. In the past, only people with a good deal of money could travel on holidays to other countries. More people travel today than in the past because there is a growing middle class in many parts of the world; that is to say, people now have more money for travel. Special plane fares(费用) for tourists make travel less expensive and more attractive than ever before. One person doesn't travel for the same reason as another. But most people enjoy seeing countries that are different from their own. They also like to meet new people and to taste new food.

    Tourism causes many changes in a country and in people's lives. People build new hotels and restaurants and train native men and women as guides to show visitors interesting places. There're new nightclubs and other amusements. International tourism is clearly a big business.

    Melinda Skaar wasn't expecting any phone calls. Skaar was working late in her office at the First Internet bank of California. By 10:45 that night she was almost ready to go home when the phone rang. Picking it up, she heard a guard shouting, "There is a fire! Get out of there." Skaar didn't panic. She figured that it was just a small fire. Her office building was huge. There were 62 floors and her desk was on the 37th floor. Skaar called out to office mate Stephen Oksas, who also stayed late to work. But when they got out to the hallway, they were met by a cloud of black smoke. Rushing back, Skaar shut the door and filled the space at the bottom of the door with her jacket to keep the smoke out.

    Then they called 911. Before they could call their families, however, the line went dead. That meant that they were completely cut off from the outside world. All they could do was wait and hope someone would come to rescue them.

    Minutes ticked by. Smoke began to float into the office. Soon it became hard for them to breathe. Looking around, Skaar noticed a small workroom. It seemed to have cleaner air. So they crowded there. That helped for a while, but in time even the workroom was filled with deadly smoke. Hopeless, they tried to break the windows, but the glass was not breakable. Everything they threw at it just bounced back. Defeated, they struggled back to the workroom. They felt weak and dizzy. Soon Skaar found Oksas had passed out.

    As Skaar and Oksas lay near death, rescuers were rushing to find them. At last, at about 4 a.m., firefighters found them.

    Skaar and Oksas knew they were lucky to be alive. Sunday is my birthday, Skaar told a reporter. She would be turning 29, but she knew she had already got the best present possible—the gift of life.

    When it comes to climate change, there are always some new, terrifying consequences to worry about—like ancient viruses and bacteria coming from the ice as the earth warms. Unfortunately, researchers fear we may see more of this in the future.

    Some of these viruses and bacteria may have been trapped for thousands of years, and it's not even totally clear yet what they are, let alone what kind of damage they might have.

    Researchers have met complex “giant viruses” in the melting permafrost(永久冻土) of Siberia. One such virus, 30,000 years old, was still infectious when it was discovered in 2015, though it posed no danger to humans. It turns out that permafrost is excellent at preserving bacteria and viruses that are temporarily inactive, and then become reactivated with warming.

    Scientists have discovered Spanish flu viruses in dead bodies buried in 1918 in the Alaskan tundra (冻原). When close to half of the population of a Siberian town in the 1890s died of smallpox (天花), their bodies were buried in the permafrost along the Kolyma River. The banks of that river are now beginning to wear away amid global warming, the BBC reports.

    In Siberia in August 2016, some 100 people and 2,300 deer were infected with anthrax(炭疽) in the first outbreak in the area since 1941. One boy died from the disease. Scientist believed the anthrax had been trapped in the body of a long-frozen dead deer and became active during particularly hot summer of 2016, releasing the bacteria cells into the environment.

But even in warmer climates, rising temperatures can help grow and spread dangerous diseases. Over a decade ago, researcher Paul Epstein prophesied the possible spread of mosquito-born illnesses as a result of climate change. “Mosquitoes are sensitive to temperature changes,” he said. “Warming speeds up their rates of reproduction and the number of blood meals they take, makes their breeding (繁殖) season long, and shortens the maturation period for the germs they spread” — all of which makes them more efficient at spreading disease.

    The skin under the eyes is delicate, which is why it sometimes appears sunken and has darker coloring than elsewhere on the face. Aging and health problems play a role in sunken eyes but other factors can contribute, so it may affect younger people as well.

Dehydration

    The most common cause of sunken eyes is dehydration, or not having enough water in the body. Consuming too much coffee, soda, and prepackaged drinks may increase production of urine(尿液), which may lead to dehydration.

    Vitamin shortages

    Shortages of vitamin C, vitamin K, and iron can cause eyes to become sunken. Vitamin C helps with absorbing iron and decreasing bruising(瘀斑), while vitamin K is responsible for blood thickening, causing unhealthy skin. Easy bruising and unhealthy skin will result in sunken eyes.

    Weight loss

    Most people tend to lose weight in their face first. Sometimes, the weight loss is sudden enough to make blood vessels(血管)below the eyes easy to see, and the skin clear, producing the appearance of sunken eyes. Sudden weight loss may also cause nutritional shortages, which can lead to sunken eyes.

    Not enough sleep or poor quality sleep can cause sunken eyes and a person's DNA or the habit of smoking can also contribute to sunken eyes. Most cases of sunken eyes relate to the quality of an individual's nutrition and healthy living. When these causes are corrected, sunken eyes can be resolved without further treatment. This means that causes can be avoided or treated in good time to prevent the recurrence of sunken eyes.