Astronauts are not like pilots, who fly into sky. They need some special trainings. They will fly into space. First they go to the Johnson space center in Houston Texas. They are tested there. Space doctors want to know how strong and smart they are.

      First of all, their hearts are tested. The people walk or run. Next, the space doctors see how fast their hearts are beating.

      Then it is another important test. In this test the person must curl his body up in a ball. And when he is in that position, he will be put into a round cloth bag. The doctors don't tell him how long he will have to stay in the bag. If a spaceship broke down in space, the astronauts would get into bags like these. Then they would have to wait, curled up in darkness, until they are saved. You can know that an astronaut must not be afraid of tight spaces or darkness.

      After these tests, scientists only choose the best people to start astronaut training in a training center. They will learn many other things in training. They will learn how to jump out of moving airplane, to blow up a lifeboat and get into it while they are in the ocean.

They also have to learn how to get lifted out of the ocean by a helicopter.

      When they finish training, the astronauts go on to work. They stay in good situation by running and doing exercise. They read about the special jobs. In that way they will be able to learn new facts about space travel.

      Finally, the astronaut is told to go to work on a flight into space. The members begin to know each other first. Then they can learn which jobs each will do.

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    Animals grow up in different ways. Some newborn animals are helpless but their mothers protect them. A newborn kangaroo is very small. It is only a few centimeters(cm) long. It closes its eyes and doesn't have hair. It stays safe in its mother' s pouch(育儿袋) for a long time.A newborn monkey can not walk. Its mother carries it everywhere.

Other baby animals can walk soon after they're born. They learn to run with their mothers when danger is near. A baby zebra can run, an hour after it is born.

    Some baby animals are born in a place that is safe. Baby wolves are usually born in big holes with little light. Other baby animals are born in the open. A baby elephant is often born on open land.

    Animals that drink their mothers' milk are called mammals. A mother bear's milk is rich. Baby bears have milk for a few months. This is the same with baby zebras. As baby animals grow, they need solid(固体) food. Baby lions eat what their mother can catch!

    Have you ever heard of e-waste, which can be produced every day? How do you deal with your computers, MP4 players and mobile phones when they're broken or you want a new one?

    Most people just throw them away. With the development of electric industry, e-waste pollution has become a serious problem. According to the United Nations, in 2014, people around the world produced 41.8 million tons of e-waste and only recycled 6.5 million tons. The US was the biggest waster, producing 7.1 million tons. China came second, with 6 million tons.

    It's important to pay attention to e-waste. It can either be valuable or harmful, depending on how we deal with it. E-waste is a valuable urban mine. The value of the metals, like gold and silver in the waste around the world, is amazing. And the metals can be reused. But if people throw them away, the toxic chemicals can get into the earth or air, effecting the environment and people's health.

    Apple, for example, now recycle people's used products in China when they are buying new ones. The company will test and repair the used ones and sell them at lower prices. To help reduce e-waste, we can also take computers and phones to see if companies offer recycling programs.

    With the development of science and technology, our daily life is becoming more colorful and more convenient .

    Artificial intelligence (AI) (人工智能）is the ability of a computer program or a machine to think and learn. It is also a field of study that tries to make computers "smart". John McCarthy, a scientist, came up with the name "artificial intelligence" in 1955. Many things such as learning and problem solving can be done by computers, though not in the same way as we do.

    An unusual goal of AI research is to create computer programs that can learn, solve problems, and think logically(逻辑地）. At present we use the term Al for successfully understanding human speech, recognizing(识别）human faces, operating self-driving cars and competing in some game systems like Chess and AlphGo（阿尔法狗）. Some people also consider AI a danger to humans if it develops too quickly. Professor Stephen Hawking (霍金), a well-known British scientist, was not for this kind of technology.

    Math is the basic language of AI. If we raise the standard in the learning of math, our students will be more likely to become successful AI designers in the future. We not only want bright students, but also need to attract average students and give them the math skills which are needed to change them into AI designers. Besides, a good knowledge of computer science is also necessary for AI designing.

    Scientists hope to create creative and emotional AI which can possibly understand human feelings or create art. Many ways and tools have been tried to discover this fascinating field.