Honey from the African forest is not only a kind of natural sugar, it is also delicious. Most people, and many animals, like eating it. However, the only way for them to get that honey is to find a wild bees' nest and take the honey from it. Often, these nests are high up in trees, and it is difficult to find them. In parts of Africa, though, people and animals looking for honey have a strange and unexpected helper—a little bird called a honey guide.

    The honey guide does not actually like honey, but it does like the wax(蜂蜡) in the beehives(蜂房). The little bird cannot reach this wax, which is deep inside the bees' nest. So, when it finds a suitable nest, it looks for someone to help it. The honey guide gives a loud cry that attracts the attention of both passing animals and people. Once it has their attention, it flies through the forest, waiting from time to time for the curious animal or person as it leads them to the nest. When they finally arrive at the nest, the follower reaches in to get at the delicious honey as the bird patiently waits and watches. Some of the honey, and the wax, always falls to the ground, and this is when the honey guide takes its share.

    Scientists do not know why the honey guide likes eating the wax, but it is very determined in its efforts to get it. The birds seem to be able to smell wax from a long distance away. They will quickly arrive whenever a beekeeper is taking honey from his beehives, and will even enter churches when beeswax candles are being lit.

    More cycling, better public transport and car bans… Places all over the world are taking a range of measures to lower traffic pollution.

Paris

    Paris bans cars in many historic central districts on weekends, places odd-even(单双日制的) bans on vehicles, makes public transport free during major pollution events and encourages car-sharing programs. A long section of the right bank of the river. Seine is now car-free and a monthly ban on cars has come into force along the Champs-Elysees.

The Netherlands

    Politicians want to ban the sale of all petrol cars from 2025, allowing only electric of hydrogen vehicles. The new law will allow anyone who already owns a petrol car to continue using it. Most cities encourage bicycle use.

Freiburg

    Freiburg in Germany has 500km of bike routes and a cheap and efficient public transport system. One town, Vauban, forbids people to park near homes and makes car-owners pay 18,000 for a space on the edge of town. In return for living without a car, people are offered cheaper housing, free public transport, and plentiful bicycle spaces.

Curitiba

    The southern Brazilian city of two million people has one of the biggest and lowest-cost bus systems in the world. Nearly 70% of its people go to work by public transport and the result is pollution-free air and traffic-free streets.

Copenhagen

    Copenhagen prioritizes(优先考虑) bikes over cars and now has more cycles than people. The city calculates that one mile on a bike is worth $0.42 to society, while one mile in a car is a $0.2 loss. Large parts of the Danish capital have been closed to vehicles for decades.

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    After years of debate, gray wolves were reintroduced (重新引进) to Yellowstone National Park. Fourteen wolves were caught in Canada and moved to the park. By 2016, the Yellowstone wolf population had grown to more than 170.

    Gray wolves once were seen here and there in the Yellowstone area and other pans of United States, but they were gradually displaced by human development. By the 1920s, wolves had disappeared from the Yellowstone area. They went farther north into the deep forests of Canada, where there were fewer humans around. The disappearance of the wolves had many unexpected results. Deer and elk populations—major food sources(来源) for the wolf—grew rapidly. These animals ate large amounts of plants, which reduced plant diversity(多样性) in the park. With the disappearance of gray wolves, coyote (草原狼) populations also grew quickly. The coyotes killed a great number of red foxes in the park, and completely drove away the park's beavers (河狸).

    As early as 1966, biologists asked the government to consider reintroducing wolves to Yellowstone Park. They hoped that wolves would be able to control the elk and coyote problems. Many framers were against the plan because they feared that wolves would kill their farm animals or pets.

    The government spent nearly 30 years thinking lip a plan to reintroduce the wolves. The U.S. Fish and Wildlife Service carefully monitors and manages the wolf packs in Yellowstone. Today, the debate continues over how well the gray wolf is fitting in at Yellowstone. Elk, deer, and coyote populations are down, while beavers and red foxes have made a comeback. The Yellowstone wolf project has been a valuable experiment to help biologists decide whether to reintroduce wolves to other parts of the country as well.

Top attractions

    Amsterdam is most famous for its artistic heritage. This tradition is proudly on display in the Rijksmuseum (translates as State Museum). Once you've taken in all that has to offer, artists, history fans, and families shouldn't pass up the chance to visit the Van Gogh Museum-containing around 700 paintings and drawings by Vincent and his contemporaries, including Gauguin, Monet, and Toulouse-Lautrec.

    Amsterdam is also home to the Anne Frank Museum, where Anne hid with her family during the Nazi occupation of the Netherlands. On a lighter note, taking a canal cruise through its extensive waterways is a rewarding way to see the Dutch capital.

    Art lovers get their kicks at:

     The Van Gogh Museum Rijksmuseum Museum het Rembrandthuis

    Food and drink

    Cheese lovers love Amsterdam. You can find an excuse to eat cheese at any time of the day here. Gouda is Holland's favorite, developing a more intense flavor the longer it's aged. Find a selection at the markets, try a cheeseboard at dinner time, or just order cubes with mustard for dipping to accompany a drink.

    When you're hungry for non-cheese food groups, you'll find Michelin-starred restaurants, vegetarian, and organic restaurants that accompany an array of global cuisine. For old-fashioned and modern Dutch food, try these Amsterdam restaurants: Moeders, Haesje Claes, Loetje, Greetje, and De Silveren Spiegel.

    Don't leave without tasting:

     Patat (hot chips with toppings) Stroopwafel (waffle cookie) Chocomel (chocolate milk)

    Amsterdam Fast Facts

    Approximate flight times:

     NYC/Newark 7 hours, 20 minutes Philadelphia 8 hours Boston 7 hours

     Miami 9 hours, 45 minutes Los Angeles 10 hours, 15 minutes

    Entry requirements: Passport must be valid for at least 3 months beyond your planned departure from the Schengen area and have 2 blank pages for entry stamp.

    Before you were my teacher, I thought that teaching was the last thing I wanted to do. Why would someone want to come in every day and attempt to instruct students, many of whom couldn't care less, or to get paid very little compared with the work he or she put in?

    You may have thought that the only thing I was learning from you was the course, but that's not all l learned. From reference books to funny jokes, you made each class exciting. You always tried to make class charming so that we could be excited about learning. However, those days have gone by.

    Whenever I was confused and needed extra help, you were the exact one to turn to. I would walk into your room for help and there would be several kids. You ran from one student to the next helping each one through their confusion. You could have gone back home after the bell rang. Instead, you chose to Stay and care about what your students did.

    You didn't only care about my learning, but you also cared about other things I was involved in. At the beginning of the year, we wrote down our hobbies and interests. You remembered what we wrote, too. I had missed class for track meets (田径运动会)and when I came back the next day, you would ask me how it went. Many of the teachers never bothered to ask what I liked to do.

    These things showed me the value of teaching. They showed me how much of an influence a teacher can have on a student. I want to be the one that influences students and pushes them toward success. I want students to leave my classroom thinking that their time was worthwhile (值得的). I want to be the inspiration for them that you were for me. Whenever it gets hard for me to continue on this path, I'll remember you and what you did for me.

    About ten men in every hundred suffer from color blindness in some way. Women are luckier; only about one in two hundred is affected in this matter. Perhaps, after all, it is safer to be driven by a woman!

    There are different forms of color blindness. In some cases a man may not be able to see deep red. He may think that red, orange and yellow are all shadows of green. Sometimes a person cannot tell the difference between blue and green. In rare cases an unlucky man may see everything in shades of green — a strange world indeed.

    Color blindness in human beings is a strange thing to explain. In a single eye there are millions of very small things called "cones". These help us to see in a bright light and to tell difference between colors. There are also millions of "rods", but these are used for seeing when it is near dark. They show us shape but no color.

    Some insects have favorite colors. Mosquitoes prefer blue to yellow. A red light will not attract insects, but a blue lamp will. In a similar way human beings also have favorite colors. Yet we are lucky. With the aid of the cones in our eyes we can see many beautiful colors by day, and with the aid of the rods we can see shapes at night. One day we may even learn more about the invisible colors around us.