Good manners are important, but you can easily make a social blunder when you visit a foreign country, because sometimes good manners in one place are bad manners in other places.

    Suppose you visit some friends in Mongolia and they ask you to eat with them. What kind of manners do they want you to have? They want you to give a loud “burp” after you finish eating. Burping shows that you like your food. But in some other countries, if you give a loud “burp”, you are supposed to say, “Excuse me, please.”

    In many places people like to eat together. But in some parts of Polynesia it is bad manners to be seen eating together. People show their good manners by turning their backs on others while they eat.

    What are manners like in an East African town? The people try not to see you. When you are visiting a friend, he may not see you at all. If you are polite, you will sit down beside him. You will wait until he finishes what he is doing. Then he will talk to you.

    If you visit a friend in Arabia you should walk behind other tents until you come to his tent. If you pass in front of other tents, you will be asked into each one. The people will ask you to eat with them. And it is bad manners if you say no.

    Manners are different all over the world. But it is good to know that all manners help people show that they want to be friends.

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    Popular music in America is what every student likes. Students carry small radios with earphones and listen to music before class, after class, and at lunch. Students with cars buy large speakers and play the music loudly as they drive on the street.

    Adult(成年人) drivers listen to music on the car radio as they drive to work. They also listen to the news about sports, the weather, and the life of American people. Most of the radio programmers（节目）are music.

    Pop or popular music singers make much money. They make a CD or tape which radio stations use in many places. Once the popular singer is heard all over the country, young people buy his or her tapes. Some of the money from these tapes goes to the singer. Wherever the singer goes, all the young people want to meet him or her. Now the singer has become a national star.

    There are other kinds of music that are important to Americans. One is called folk music. It tells stories about the common life of Americans. Another is called western or country music. This is started by cowboys（牛仔）who would sing at night to the cows they were watching. Today, any music about country life and the love between a country boy and his girl is called western or country music.

    When people see machines that respond like humans, or computers that perform amazing feats of strategy, they sometimes joke about a future in which humanity will need to accept robot overlords. But buried in the joke is a seed of unease. Science fiction writing and popular movies have shown us about artificial intelligence (AI) that exceeds the expectations of its creators and escapes their control, eventually outcompeting and enslaving humans or targeting them for extinction(灭绝).

    Even in the real word, not everyone is ready to welcome AI with open arms. In recent years, as computer scientists have pushed the boundaries of what AI can accomplish, leading figures in technology and science have warmed about the frightening dangers that artificial intelligence may pose to humanity, even suggesting that AI capabilities could destroy the human race.

    But why are people so frightened about the idea of AI?

    Elon Musk is one of the famous voices that have raised red flags about AI, In July 2017. Musk told attendees at a meeting of the National Governors Association, I have exposured to the very cutting-edge Al, and I think people should be really concerned about it. I keep sounding the alarm bell. But until people see robots going down the street killing people, they don't know how to react, because it seems so impossible."

    Earlier, in 2014, Musk had labeled AI "our biggest existential threat," and in August 2017, he declared that humanity faced a greater risk from AI than the terrorists. Physicist Stephen Hawking, who died on March14, also expressed concerns about AI, telling the BBC in 2014 that "the development of full artificial intelligence could spell the end of the human race.

    Police Officer Tidwell left the station just after 8 a.m. on Sunday June 4. He had spent a boring night on duty and was looking forward to his day of rest. By habit he took a short-cut down the path behind Dugby Hall road and after a minute or two he saw a man climbing down a drainpipe (雨水管)from an open bedroom window of Number 29. In silence, Tidwell crept into the garden. The man reached the ground and was dusting himself down when he felt his arm caught.

    "It's 8:15 on a Sunday morning," said the officer, "and this sort of thing seems an unlikely adventure at such a time. Would you mind explaining?"

The man was obviously scared but tried to keep calm. He said, "I know what you are thinking, officer, but it isn't true. This is a funny mistake."

    "It's part of my job to take an interest in unusual events. I think you've just left this house in a manner other than the customary one. That may be quite innocent, but I'd like to make sure." Tidwell took out his notebook and a pen. "Name, address and occupation and then, please, tell me your story..."

    "Charlie Crane, lorry driver, from Nottingham, 51 Breton Street. My story..."

    "Yes. What were you doing like a fly on that wall, Mr. Crane?"

    "Well, I had a breakdown yesterday and had to stay the night here. Bed and breakfast. The land-lady's name is Mrs. Fern. She gave me breakfast at seven, and I was out of he: mthe right way and down at the lorry by half past seven. Only when I felt around for a cigarette did I realize I'd left $80 in my envelope under the pillow here at number 29. I always put it under my pillow at night. It's a habit I've got into. I even do it at home...

    "I see. Why didn't you miss it when you went to pay Mrs.... What's her name?"

    "I'd paid her last night. You've got to pay when you take the room, see? So I came rushing back, but it's Sunday, and she'd gone back to bed, and could I wake her? I rang the bell and banged on the front door for ten minutes before I came round here to the back and spotted my bedroom window still open. Up I went, then, up this pipe. It's a trick I learned in the army. She didn't make the bed、and money was still there. You know the rest, I hope you believe it because... "

    "Mr. Crane, whatever are you doing here? I thought you'd gone an hour ago." It was Mrs.  Fem, speaking from the kitchen at the corner of the house.

    I stopped to watch my little girl busy playing in her room. In one hand was a plastic phone ; in the other a toy. I listened as she was speaking to her make-believe little friend and I'll never forget the words she said, even though it was imagined.

    She said, "Suzie's in the corner because she's not been very good. She didn't listen to a word I said or do the things she should." In the corner I saw her baby doll well dressed. It was obvious that she'd been put there to sit alone and think.

    My daughter continued her "conversation", as I sat down on the floor. She said, "I'm all fed up and I just don't know what to do with her any more. She cries whenever I have to work and wants to play games too. She tries to help me with the dishes, but her arms just cannot reach... And she doesn't know how to fold towels. I don't have the time to teach. I have a lot of work to do and a big house to keep clean. I don't have the time to sit and play - don't you know what I mean?"

    And that day I thought a lot about making some changes in my life, after listening to her innocent words which cut me like a knife. I hadn't been paying enough attention to what I hold most dear. I'd been caught up in responsibilities that increased throughout the years.

    But now my attitude has changed because in my heart I realize that I've seen the world in a different light through my little darling's eyes. So let the cobwebs(蜘蛛网) cut the corners and the dust bunny rabbit rule the floor. I'm not going to worry about keeping up with them anymore.

    I'm going to fill the house with memories of a child and her mother, for we have only one childhood and we will never get another.

Myopia, also known as nearsightedness, has become a lot more common in recent decades. Some even consider myopia an epidemic (流行病). But what causes myopia and what reduces it?

While having two myopic parents does mean you're more likely to be nearsighted, there's no single myopia gene. That means the causes of myopia are more behavioral than genetic.

Scientists have learned a great deal about the progression of myopia by studying visual development in baby chickens. They do so by putting little hats on baby chickens. Lenses (镜片) on the face of the hats cover the chicks' eyes and are adjusted to affect how much they see.

Just like in humans, if visual input is wrong, a chick's eyes grow too large, resulting in myopia. And it's progressive. Blur (模糊) leads to eye growth, which causes more blur, which makes the eye grow even larger, and so on.

Two recent studies featuring extensive surveys of children and their parents provide strong support for the idea that an important driver of the increase in myopia is that people are spending more time focusing on objects immediately in front of our eyes, whether a screen, a book or a drawing pad.

Other research has shown that this unnatural eye growth can be interrupted by sunlight. A 2022 study, for example, found that myopia rates were more than four times greater for children who didn't spend much time outdoors—say, once or twice a week—compared with those who were outside daily. At the same time, kids who spent more than three hours a day while not at school reading or looking at a screen close-up were four times more likely to have myopia than those who spent an hour or less doing so.

Fortunately, just a few minutes a day with glasses that correct blur stops the progression of myopia, which is why early vision testing and vision correction are important to limit the development of myopia.