Goldfish have pretty boring lives, so maybe it's good thing they can only concentrate for nice seconds! But according to new research, humans are becoming like goldfish. Our attention span (时长) is getting shorter ... and it's all because of

    "We move quickly from one site to another on the web," says Doctor Ted Selker, a computer scientist from Massachusetts," and we are losing the ability to concentrate." With millions of websites to choose from, the attention span of the internet user is just seconds. There are other digital distractions (分心) too: email, instant messaging and quickie movies on websites. Some people are worried about the effect on young people. "You need time to understand and what you read." says Julia Wood, from London. "Young people search the net all the time and their brains become full of useless information but there is no time to make sense of it. I am trying to my pupils to read more books, so that they concentrate on one subject for longer."

    Other teachers are trying more unusual to improve students' concentration. Anne Savan, from Wales, was so worried about her students that she started playing Mozart during her science lessons. She says that it had an amazing effect: " The music made them , and their concentration was much better."

    But not everyone believes that there is a problem. Ray Cole, an educational psychologist says: " On the web, young people learn to make quick decisions about what is and isn't reading.

    They might look at five unhelpful websites very quickly, before stopping and reading a sixth useful website more . In a word with so much information available, this is an important skill."

A Cloud of Hope and Danger

    In 2050, a small cloud floats through the air in a hospital operating room(手术室). In the room a patient, suffering from cancer, lies on a table. The cloud surrounds (包围) the patient, her body and filling her lungs (肺). The cloud is not smoke or steam. It is made of millions of microscopic robots called nano-robots(纳米机器人). These tiny robots move from cell(细胞) to cell in the body, destroying the cancer cells.

    Fighting cancer with nano-robots is only an idea today, scientists say that it would be possible in the future. Using nano-robots for good purposes such as fighting disease or repairing the environment may be the to many of today's problems.

    However, nano-robots could be a risk as well. Since nano-robots are so tiny, they will have to work in large teams of many thousands to 'many millions. For this reason, nano robots will have to be programmed to build . Scientists will not have the ability to build millions of nano-robots one by one.

    This to reproduce(复制)is making some scientists worried. What if something goes wrong in the programming? Quite a lot of crazy nan-orobots would be far than any disease. Some people think that if they get out of control, nan-orobots could destroy the Earth.

    What should be done? Should we continuenan-orobots or should we search for other methods? This is one of the many difficult that we have to make in the future.

Laughter is good for you, and that's no joke! A good laugh helps you right away. When you laugh, changes in your body. For example, you take in  air than usual, which is good for your heart. A good laugh increases your heart rate. When you laugh, your brain also releases (释放) chemicals that make you feel happy. Laughing can also make you feel relaxed for up to 45 minutes.

Laughter can  reduce pain. You probably don't want to chuckle (偷笑) when you're hurt, but laughter helps the body make its own  medicine. Laughing is also great exercise! Research  that laughing 100 times is as good as riding a bike for 15 minutes.

So why don't you try laughing out loud every day?

When the other models appeared on the stage, the audience cheered and clapped. Then it was Niu's turn. The audience suddenly became . However, after four or five seconds, Niu heard someone next to the stage say in admiration, "So cool!"

Niu Yu, 24, became a(n) star at Shanghai Fashion Week for her confidence, even though she was wearing a prosthetic leg. When Niu was only 11, she lost her right leg during the Wenchuan Earthquake.

Niu has won lots of praise. This gives those who have prejudice(偏见)against the disabled a hit on the nose. "I by something they said. They said the traditional view was that sports were for people with legs, but sports should be a kind of spirit. Even though I have lost a leg, I still deeply love sports and will do so forever, " Niu said. Actually, Niu first drew the public's attention when she a marathon — a 42-kilometer race in 2018, which was held in Wenchuan to mark the anniversary （周年纪念）of the earthquake.

Now, Niu works as a photographer and has more than 850,000 on social platforms, such as Douyin. "I feel I have a social responsibility to bridge the disabled and the public. Showing my life to the public can allow them to understand our group and can also tell other disabled people that our society is more tolerant（宽容）than they imagined, " she explained.