Scientists have always believed that snails are not able to find their way home. But Briton Ruth Brooks, a retired teacher, has found that it is not true.

    Brooks began an experiment on snails after she got mad with the snails in her garden.

    The snails had eaten her vegetables. She didn't want to kill them, so she took them to another place. But she found they always seemed to come back.

    Brooks did an experiment. She marked the snails in her garden with nail polish(指甲油).

    She placed the snails in the area around her home and made notes of their movements.

    She found that snails have a strong homing instinct (本能); the longest returning snail traveled back 90 meters. Brooks has been named Britain's best amateur (业余的) scientist after her work won the BBC Radio 4 project, So You Want To Be A Scientist.

    She said, "I've always wanted to know whether the snails that eat my plants just come back when I move them, and if they do, what is their homing distance?

    "I would say on the evidence (证据) that it would be safe to take your snails away beyond 100m or even further. If you put them somewhere nice with some food, you can be almost certain that they won't come back."

    Imagine this. You come back from school and your robot housekeeper is already waiting for you at the door. He turns on the lights, air-conditioner and television. While you are having dinner, he cleans the floor. Before you go to sleep, he tells you the weather report, then reads you a bedtime story.

    Such thoughts are not just for stories. Now they can happen in the real world, as long as you have the robot Alpha 2. Alpha 2 was a star at the 2017 World Robot Conference(大会), which was held from August 23^rd to 27^th in Beijing. More than 150 universities and companies from across the world brought their robots to the event for show and sale. Some robots work in factories. Some robots go to outer space or under water for exploration. But the highlights(亮点)of the event were service robots.

    This kind of robot is the closest to our daily lives. From cleaning to teaching, music to sports, service robots have been used to do many kinds of jobs.

    Teo is a popular service robot, as well as an artist and music teacher. His 53 fingers help him play the piano well. He played John Lennon's song Imagine at the conference.

    There is another service robot called Bestic. It acts as a human arm to feed people with a spoon. It can be a good helper for little kids, the elderly and those with difficulties using their hands.

    The scientists believe that it may not be far when every family has at least one service robot.

    On July 20, 1969, Neil Armstrong became the first person to walk on the moon. The space suit Armstrong wore on his lunar mission has come to symbolize courage and human achievement. In 1971, the Smithsonian's National Air and Space Museum(NASM), in Washington, D.C., acquired (获得) Armstrong's suit. It stood proudly on display for visitors to admire, until there were changes in the suit's appearance. "Over time, the suit started to show signs of deterioration," Lisa Young said. Young is an objects conservator (文物修复员) at NASM. It is her job to preserve(维护)historical and cultural objects.

    "Plastics are tricky to conserve," Young says. They tend to degrade (降解)over time. Neoprene is one type of plastic in Armstrong's suit. The material can turn brittle and break into tiny pieces. This would ruin the space suit. NASM, seeking ways to preserve this historical treasure, removed it from display in 2006.

    What causes plastic to degrade in the first place? "Many things," Odile Madden says. Madden is a scientist in California. She explains that sunlight, water, humidity, and dust can cause plastics to degrade. "Some plastics will break down no matter what we do," Madden says.

    Yet history can still be saved. Scientists have found that storing plastics in cooler temperatures, with lower humidity levels, can slow degradation. Young says Armstrong's suit is currently in storage at a temperature of 63°F and a lower relative humidity of 30%. These conditions will be maintained when Armstrong's suit returns to a museum display case in time for the 50^th anniversary of the moon landing.

    Plastic degradation affects art, too. Artist Claes Oldenburg created False Food Selection in 1966.It consists of plastic food displayed in a wooden box. The plastic food used to look real. Now, some of it has flattened and yellowed. Georgina Rayner is a conservation scientist at Harvard Art Museums, in Cambridge. She says the artwork's wooden box produces an acidic (酸的) gas that eats away at the plastic. This speeds up the degradation process. But Rayner is motivated to conserve this artwork and others like it. "Plastics are a part of our history," she says. "It's important to preserve them so that future generations can understand the journey we've taken."

    Everybody hates rats. But rats may soon be man's new good friends. What happens after an earthquake? We send in rescue dogs. Why? Because they can smell people. Dogs save lives. They help rescuers to find living people. But dogs are big and they can't get into small spaces. So now a new research project is using a smaller animal to save lives: the rat.

    How does it work? First, the rat is trained to smell people. When this happens, the rat's brain gives a signal. This is sent to a small radio on its back, and then the rescuers follow the radio signals. When the rat's brain activity jumps, the rescuers know that someone is alive. The rat has smelled that person.

    Although there are already robots which can do this job, rats are better. Robots' noses don't work well when there are other smells around. Rats are good at that. Rats can also see in the dark, they are cheaper and quicker to train than dogs, and unlike robots, they don't need electricity!

    The "rat project" is not finished. But a scientist says, "It would be great. A rat could get into any place we couldn't get to, and a rat would get out if it wasn't safe." Perhaps for the first time in history, people will be happy to see a rat in a building (but only after an earthquake, of course).

    Linda and Lily are sisters. Linda is fourteen1old and Lily is eleven. They2in Beijing with their parents this year. They are3in Beijing, so they don't know much about it. They are students, but they are not in the same school. Linda's school is not near (在……附近) her home. How4is it from her home to school? It's about five kilometers. So she usually goes to school5bus. She walks to the bus stop near her home first. And then she6a bus to school.7usually takes her half an hour to get to school.

    Lily's school is8one kilometer from her home. She usually9her bike to school.10when she gets up early sometimes, she will walk to school. She likes walking in the fine weather (天气). When she goes to school by bike, it usually takes her ten minutes. When she walks, it always takes her twenty — five minutes.

My cousin Tommy was born in a small city in 2009. It's in the {#blank#}1{#/blank#} (西方) of Germany, and it has a population of about 2,000,000. There are lots of things to do, with a library, a park, a zoo and a{#blank#}2{#/blank#} (体育馆). Tommy likes playing basketball, he thinks it is an {#blank#}3{#/blank#} (激动人心的) sport. He does well in it. The city is also famous for its beautiful lakes and some famous {#blank#}4{#/blank#} (大学).

Last weekend, the weather was fine. Tommy's classmates wanted to play with him. Tommy {#blank#}5{#/blank#} (提议) to go to the zoo. There were many people in it, so it's very {#blank#}6{#/blank#} (拥挤的). The children were all interested in the animals from foreign countries, especially pandas. They all {#blank#}7{#/blank#} (同意) that pandas were very cute. {#blank#}8{#/blank#} (然而), they were sorry to know that pandas and many other animals were in {#blank#}9{#/blank#} (危险). Many wild animals don't have a safe place to live, and what's more, there isn't enough clean water to drink. At last, they decided to save their pocket money to help {#blank#}10{#/blank#} (保护) animals.