Many animals hide to stay alive. They hide in many ways. Some animals hide in leaves; some animals hide in snow. Usually their colors or shapes help protect them. It's hard to see an Arctic bear in snow. Its white fur helps protect it. Chameleons(变色龙) can hide by changing colors. Their skin turns the same color as what is around them. Some chameleons can change colors in five minutes.

    Many animals try to look bigger than they are to stay alive. Some animals can make other animals think they are very big. If they look very big, animals that are looking for food will run away. Bears can walk on two legs. They look very, very scary. Some animals will run away from them.

Many animals try to stay around other animals. This helps them stay alive. Zebras stay close together so that they can help each other look out of danger. Seeing many stripes at once can also confuse animals that want to eat them. Some birds stay in a circle, each toward a different direction. In this way they can also help each other stay alive by looking around for animals that many want to eat one of them.

Researchers have discovered the first Earth-sized planet. It was first marked by NASA's Kepler telescope(望远镜) so it's called Kepler-186f. It lies about 500 light years from Earth and goes around its star. The planet is the right distance from its star for water: not too close or not too far. Water is one important condition that scientists guess is necessary for life. So it could have water and possible life. It's called a true Earth cousin.

"This planet is an Earth cousin, not an Earth twin," said Barclay, who is among a team of scientists reporting on the discovery in the magazine Science this week.

"It's very exciting to find a planet similar to the Earth," Barclay said, "It's not easy work because things change as we get more measurements."

Scientists don't know anything about the air of Kepler-186f, but it will be a task for future telescopes which can study for chemicals that have something to do with life.

    "It's possible for life to live in this planet, but that doesn't mean there is life in it," Barclay said.

So far, scientists have found nearly 1,800 planets in the universe.

"The past year has seen a lot of progress in the search for Earth-like planets. Kepler-186f is very important because it is the first planet that is the same temperature and is almost the same size as Earth," scientist David Charbonneau wrote in an email.

    People already know a lot about animals. However, there are still some things about animals that may surprise you. Here are some facts about animals you probably didn't know.

    Cows do have best friends and feel stressed when they are separated. Scientists have found that cows are very social animals and a cow always makes friends with other cows. When a cow is with its friends, it feels relaxed, compared with when it is alone.

    During breeding season, a male penguin (企鹅) will offer a small stone to a female penguin as a gift. If she takes it, they will become partners. When the female penguin lays an egg, she and her partner may carry it on their feet, because some penguins don't build nests (鸟巢).

    Crocodiles (鳄鱼) swallow (吞) stones. Crocodiles always swallow their food instead of eating it like other animals. They swallow stones which break the food into very small pieces in their stomachs. These stones may stay in their stomachs all their lives.

    Elephants use plants to treat pain or other illness. Scientists once found a pregnant (怀孕的) elephant in Africa who ate a kind of plant which was not part of her normal food. Four days later, she gave birth to a baby elephant. The same plant was used by the local pregnant women.

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    In most parts of the world, many students help their schools make less pollution. They join "environment clubs". In an environment club, people work together to make our environment clean.

    ●No-garbage lunches. How much do you throw away after lunch? Environment clubs ask students to bring their lunches in bags that can be used again. Every week they will choose the classes that make the least garbage and report them to the whole school!

    ●No-car day. On the no-car day, nobody comes to school by car—not the students or not the teachers! Cars give pollution to the air, so remember:

    Walk, jump, bike or run.

    Use your legs! It's lots of fun!

    ●Turn off the water! Did you know that some toilets can waste twenty to forty liters (升) of water an hour? In a year that would fill a small river! In environment clubs, students mend those broken toilets.

    We love our environment. Let's work together to make it clean.

    The Wandering Earth(流浪地球), China's first successful movie whose background is space, as shown on February 5. It is based on(基于)a short story of the same name by Liu Cixin, China's top  science—fiction writer.

    ⒈Capsule(太空舱)—a core(核心)element(要素)

    The space capsule used in the film has made the audience(观众)interested. "This was the first time anything like that was done, "said Wang Hong, the producer(制片人)of the movie. At first, the production(制作)team planned to use a small space capsule that had appeared in an earlier film, but found that it could not meet their needs for filming.

    ⒉Giant vehicles(巨大的车辆)—key to the film

    Giant vehicles are the key element in the film. Famous actors, Ng Man—tat and Wu Jing, said they could not even imagine what these vehicles would be like before filming, because the idea was far ahead of our time.

    The production team made about 10, 000 props(道具)to show the space better, including the giant vehicles.

    ⒊Saving planet itself

    In the film, the earth itself is pushed forward by 10, 000 giant

thrusters(推进器). It carries 3.5 billion people about 4.2 light years

through space in order to avoid destruction(破坏)by the dying sun.

In Liu's story, each thruster is 11, 000 meters in height.

    ⒋Amazing opening

    At the beginning of the film, it shows the environment and life in an

underground city—a big tree growing upside down, busy bookstores and snack bars and so on. There are also many snow scenes (片段)throughout the whole film.