When we know somewhere well, we say we know it like the back of our hand.

【小题1】.

Wider and shorter

Professor Matthew Longo, at the University of London. tried an experiment. His team of researchers covered the left hands of 100 people. Then they asked these people to point to where they thought their fingertips and knuckles (指关节）were.

【小题2】.People think their hand is wider and their fingers are shorter. " said Longo.

Sense of position

"It is connected to our sense of position, explained Longo. This is our ability to tell where different parts of our bodies are, even when we can't see them."【小题3】 ," he said. "It also tells us whether we are going up or down in an elevator. " All this information comes from signs from nerves( 神经）.It's like our brain has maps-maps that show the size and shape of our body. "This experiment tried find those maps, said Longo.

【小题4】

But these maps make mistakes. These mistakes may be made because of how the brain understands different parts of the skin. Our brains 'see' areas as larger where the skin feels touch strongly," said Longo. Body parts don't appear as their true size, but appear bigger or smaller depending on how strongly they feel touch. Our lips, for example, have more nerves than our nose.' So the brain "sees" lips on its map of the body as being bigger than our nose.

With her eyes always feeling tired, 16-year-old Sun Run went to the hospital with her parents in January. She was shocked when she found out that her eyesight dropped from 5.0 to 4.6 in only 5 months. “A few of my friends have had the same experience lately,” Sun said.

In fact, poor eyesight among Chinese primary and middle school students rose from 59.2 percent to 70.6 percent in the first six months of 2020, according to the Ministry of Education (教育部).

To protect students’ eyesight, the Chinese government has worked out new requirements (要求) for schools. For example, according to the requirements, the size of text in students’ textbooks should be no smaller than nine-point (小五号). Teachers should also avoid (避免) using projectors (投影仪) or other multimedia equipment (多媒体设备) that are too bright, Beijing Daily reported.

There are also requirements for desk and classroom lights. For example, these lights should give off as little blue light as possible. Blue light is bad for our eyes, as it can kill the photoreceptor cells (感光细胞) we need, according to Harvard Medical School. Many of the electronic devices (电子设备) we use every day, including our phones and computer screens, give off blue light.

Chinese government has also taken other steps to protect students’ eyesight in China. In May 2020, schools were asked to make sure that students have at least two hours of outdoor activities a day.

If you do not use your arms or your legs for some time, they will become weak, and when you start using them again, they slowly become strong again. Everybody knows that. Yet many people do not seem to know that memory works in the same way.

When someone says that he has a good memory, he really means that he keeps his memory in practice by using it. When someone else says that his memory is poor, he really means that he does not give it enough chance to become strong.

If a friend says that his arms and legs are weak, we know that it is his own fault (过错). But if he tells us that he has a poor memory, many of us think that his parents may be blamed, and few of us know that it is just his own fault. Have you ever found that some people can’t read or write but usually they have better memories? This is because they cannot read or write and when they have to remember things, they cannot write them down in a small notebook. As a result, they have to remember days, names, songs and stories, so their memory is being exercised the whole time.

So if you want to have a good memory, learn from the people: practice remembering things in a way as other people do.