In some science fiction movies, evil robots refuse to die, no matter how hard people fight back.

    Now science fiction has become science fact. For the first time, scientists have made a robot that can take a beating (挨打) and keep on going. Scientists from Cornell University made the robot, which looks like a spider with four legs.

    Until now, even the most advanced (先进的) robot was almost certain to break down when it was damaged. That is because its computer inside simply doesn't know how to make the machine work after its shape has changed.

    To deal with this problem, the scientists put eight motors (发动机) and two sensors (传感器) that read how the machine is working. They all give signals to the machine's software. Using this information, the computer can then figure out the machine's shape at any moment.

    The new technology is a big advance in robot-making, scientists say, and it's far from scary. It may someday help scientists create better artificial (假的) arms and legs and give new freedom to people who lose them. It might also help scientists understand how people and animals figure out their own sense of place in space.

    “It has been difficult to design robots that can work well when the environment changes or when it's damaged,” says Olaf Sporns of Indiana University in US. “With this work, we are nearer to solving this problem.”

    Canada Geese are large blue and white birds. When autumn comes, they have to fly south where the weather is warmer. The winters are so cold in Canada that the birds will die if they stay there.

Last spring, Bill Lishman found sixteen young Canada Geese on his farm. They had lost their parents. Bill thought, "These young birds won't know what to do in the autumn." He had a small plane and he decided to teach the birds to fly by following him. All through the summer, he went on short trips in his plane and the young geese flew after him.

When the cold weather arrived in the autumn, Bill flew to Virginia in the United States——600 miles South of his home in Canada. The geese followed him all the way. Bill left the geese in Virginia and he returned home.

    This spring, Bill was waiting for the birds to come back. They didn't arrive, so Bill flew to Virginia to get them. He looked for them for two weeks but he couldn't find them. When he arrived back home, he found the geese waiting for him. They had found their way home without him!

( No more than 4 words)

    Clothes are traditionally made of natural materials, such as cotton, leather and wool. They are all from plants or animals, but that doesn't mean they're friendly to the earth. For example, farmers have to use a lot of chemicals to grow cotton plants.

    Scientists are now looking for new ways to make clothing materials. They hope the new materials are both comfortable and good for the earth. Scientists have worked out how to make materials out of corn husks(棉籽), chicken feathers and rice straws.

    "They used to be useless things. We always have a problem of how to deal with them," Yang, a scientist says, "Now, we can turn them into beautiful materials. Chicken feathers are better than other things. They have small air pockets like honeycombs. That means it will be very warm if you use them to make a jacket or sweater, and I think more and more people will like to buy these kinds of clothes."

    Sheridan is a town in Indiana, USA. There are lots of trees near the public schools in the town. Their leaves turn sunlight into energy（能量）.

    In Sheridan, the sun not just provides energy for plants. It keeps schools running, too. The schools use solar panels（太阳能电池板） to turn sunlight into energy.

    The science behind solar energy is not new. But Sheridan Community Schools is the first school district(学区) in Indiana to be completely solar-powered. The district finished putting in solar panels for all three of its schools in 2016. Some of the panels can turn to follow the sun across the sky.

    In 2008, fewer than 1. 000 schools used solar power. By 2014, there were 3, 727 schools with solar panels in the USA. These numbers come from a report by the Solar Foundation. Roxie Brown, a program director there said that the number of schools with solar panels has continued to go up since 2014.

    Solar energy has some advantages over other energy sources(来源). Sunlight is a renewable source, which means it won't run out. Solar panels don't harm the environment. Also, sunlight is free. So by using solar power, schools can save money on energy costs.

    Brown thinks more schools should run on solar energy. "The sun is Earth s energy source," she says. "We're trying to make it the energy source for our houses cars and schools, too."

    But using solar energy isn't always easy. Solar panels can be expensive to put in. The panels also take up space. But for many schools, going solar is worth it.

    If there is no rain, there will be no water to drink. We can only live for about three days without water. If there is no rain, we'll have no water to brush our teeth. We will have no water to take a shower. We will have no water to wash dishes or our clothes.

    Plants and animals need water to grow. If there is no rain, they will die. We will not have any rice, any vegetables or any meat. If there is no rain, we will have nothing to eat. We can only live for about one or two weeks without food.

    If there is no rain, there will be no water in the streams or rivers. Fish will have nowhere to live. They will die. We will have nowhere to swim.

    If there is no rain, the cooks in the restaurants will have no water to cook food.

    If there is no rain, firemen will have no water to put out fires.