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.

    How long is a year? Most people say a year is 365 days. It takes about 365 days for the earth to go around the sun. In fact, it takes a little longer for the earth to go around the sun. It needs 365 days, 5 hours, 48 minutes, and 46 seconds.

    If a year has only 365 days, what happens to the extra(额外的) 5 hours, 48 minutes, and 46 seconds? The answer is this: Every four years, we have another day. It's February 29, and we call this day " a leap day(闰日)".This kind of year is called "a leap year". A leap year has 366 days.

People born on February 29 are called leap-day babies, or leapers. There are about four million leapers in the world. When do they celebrate their birthday? Do they celebrate only once every four years? Some leapers celebrate the birthday on February 28, and others celebrate it on March 1. Think about it: A twelve-year-old leaper may have celebrated only three birthdays on the real day after he or she was born!

    Which year are leap years? Years that can be divided(除尽)by four are leap years. The year 2000 was a leap year. Then 2004,2008,2012,2016 were the next leap years. If you know a leaper, you must say "Happy birthday!" to him or her on the leap day, because you just have one time to do that every four years!

    Some people seem to have unusual memories. Zheng Aiqiang, a "memory athlete" on TV show Super Brain, can remember 2,660 numbers in just one hour!

    You would think people like him must have special brains. But according to a recent study by researchers from America and Holland, the brain structure (结构) of ordinary people and 23 of the world's leading memory athletes shows no difference.

    Good memories can be trained. New research in the magazine Neuron suggests that a person will get a super memory with just six weeks of hard training.

    Researchers found that a technique (技巧) called loci, invented by the ancient Greeks, can greatly help improve memory.

    By using loci, you are using your imagination to improve the brain's memory networks. You can link (关联) something you need to remember with a place that you know very well. For example, to remember a list of numbers, imagine yourself walking through your house. Each thing is linked to a number. For example, zero could be the handle on the door and five could be the painting on the wall.

    In one study, some ordinary people were given 20 minutes to remember 72 nouns. At the beginning, they could only remember 26 words, but when they were taught loci, they could remember 62 words.

"Not everyone can become a memory winner. But everyone using the technique can improve his memory greatly," said Boris Konrad, one of the researchers in the study.

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    Everyone knows the strange feeling of your fingers wrinkling up (起皱) when they're wet. Sometimes when in water, it seems as if your hands have aged 30 years in a second. But is this an accident? Or is it something that nature has built into our bodies?

    Scientists at the University of Newcastle in the UK recently did a test. They asked people to pick up things (some wet and some dry). And take them from one place to another. Some people did this with dry hands, while others had to leave their hands in water for 30 minutes first so that their skin was wrinkled. The study found the second group with wet hands had an advantage when carrying things that were also wet.

    The scientist Tom Smulders said that "this wrinkling of our fingers in wet conditions could have helped with gathering food from wet vegetation or streams". Wrinkling happens when blood vessels contract (血管收缩) and pull the skin back.

    A long time ago, humans lived a very difficult life in a brutal world, where the smallest advantage could make a huge difference. Having wrinkled skin might have helped people catch fish. This would help them get through the winter. These humans would then have had an advantage. Their genes would be accepted by natural selection.

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Breakdancing, also known as breaking, will be an Olympic sport for the first time in 2024. To attract younger people to watch sports games, breaking is becoming a new event at the 2024 Paris Olympic Games. Paris 2024 Olympics will see 16 b-boys and 16 b-girls compete in one-on-one “battles”. The top finishers will get the Olympic prize.

Breaking is a kind of street dance. It is also part of the hip hop movement. It grew up together with hip hop during the early 1970s. It was really popular among African American and Latin American young people.

In the past, people wouldn't believe that street dance could become an Olympic sport. However, it comes true now. When the International Olympic Committee says breakdancing will be added to the 2024 Paris Olympic Games, a lot of people are excited. “It is a historic time not only for b-boys and b-girls, but for all dancers around the world. We thank everyone who helped make it possible,” says Shawn Tay, president of the World DanceSport Federation (WDSF). WDSF is happy about the result and it will prepare for the breakdancing competition to make the event unforgettable.

Skateboarding, surfing and rock-climbing are also becoming the 2024 Paris Olympic events. In fact, the three new sports have already been added to the program for the 2021 Tokyo Olympics. These new sports are going to make Olympics more attractive.