Tom appeared on the sidewalk with a bucket of whitewash and a long­handled brush. He stopped by the fence in front of the house where he lived with his aunt Polly. He looked at it, and all joy left him. The fence was long and high. He put the brush into the whitewash and moved it along the top of the fence. He repeated the operation. He felt he could not continue and sat down.

    He knew that his friends would arrive soon with all kinds of interesting plans for the day.

    They would walk past him and laugh. They would make jokes about his having to work on a beautiful summer Saturday. The thought burned him like fire.

    He put his hand into his pockets and took out all that he owned. Perhaps he could find some way to pay someone to do the whitewashing for him. But there was nothing of value in his pockets—nothing that could buy even half an hour of freedom. So he put the bits of toys back into his pockets and gave up the idea.

    At this dark and hopeless moment, a wonderful idea came to him. It filled his mind with a great, bright light. Calmly he picked up the brush and started again to whitewash.

    While Tom was working, Ben Rogers appeared. Ben was eating an apple as he walked along the street. As he walked along it, he was making noises like the sound of a riverboat. First he shouted loudly, like a boat captain. Then he said “Ding－Dong－Dong”， “Ding－Dong－Dong” again and again, like the bell of a riverboat. And he made other strange noises. When he came close to Tom, he stopped.

    Tom went on whitewashing. He did not look at Ben. Ben stared a moment and then said: “Hello! I'm going swimming, but you can't go, can you？”

    No answer. Tom moved his brush carefully along the fence and looked at the result with the eye of an artist. Ben came nearer. Tom's mouth watered for the apple, but he kept on working.

    Ben said, “Hello, old fellow, you've got to work, hey？”

    Tom turned suddenly and said, “Why, it's you, Ben! I wasn't noticing.”

    “Say—I'm going swimming. Don't you wish you could? But of course you'd rather work—wouldn't you? Of course you would.”

    Tom looked at the boy a bit, and said, “What do you call work？”

    “Why, isn't that work？”

    Tom went back to his whitewashing, and answered carelessly.

    “Well, maybe it is, and maybe it isn't. All I know is, it suits Tom Sawyer.”

    “Oh come, now, you don't mean to say that you like it？”

    The brush continued tomove.

    “Like it? Well, I don't see why I shouldn't like it. Does a boy get a chance to whitewash a fence every day？”

    Ben stopped eating his apple. Tom moved his brush back and forth, stepped back to look at the result, added a touch here and there, and stepped back again. Ben watched every move and got more and more interested. Soonhe said，“Say, Tom, let me whitewash a little.”

    Tom thought for a moment, and was about to agree, but he changed his mind.

    “No—no—it won't do, Ben. You see, Aunt Polly wants this fence to be perfect. It has got to be done very carefully. I don't think there is one boy in a thousand, maybe two thousand, that can do it well enough.”

    “No—is that so? Oh come, now—let me just try. Only just a little.”

    “Ben, I'd like to, but if it isn't done right, I'm afraid Aunt Polly … ”

    “Oh, I'll be careful. Now let me try. Say—I'll give you the core of my apple.”

    “Well, here—No, Ben, now don't. I'm afraid …”

    “I'll give you all of it.”

    Tom gave up the brush with unwillingness on his face, but joy in his heart. And while Ben worked at the fence in the hot sun, Tom sat under a tree, eating the apple, and planning how to get more help. There were enough boys. Each one came to laugh, but remained to whitewash. By the time Ben was tired, Tom sold the next chance to Billy for a kite; and when Billy was tired, Johnny bought it for a dead rat—and so on, hour after hour. And when the middle of the afternoon came, Tom had won many treasures.

    And he had not worked. He had had a nice idle time all the time, with plenty of company, and the fence had been whitewashed three times. If he hadn't run out of whitewash, Tom would have owned everything belonging to his friends.

    He had discovered a great law of human action, namely, that in order to make a man or a boy want a thing, it is only necessary to make the thing difficult to get.

    The end of the school year is in sight — Christmas cards, candy canes and of course, end of year reports.

    While most parents welcome an assessment of their kids' performance, they do not expect their own input to be evaluated. But a school in the UK is changing that. As well as assessing their students, they are dishing out grades to mums and dads. Parents that are really involved in their kids' education are rewarded with an A, and parents that haven't done their bit get a disappointing D.

    The school, Greasley Beauvale Primary in Nottinghamshire, uses standard such as whether mums and dads have attended school events such as plays and parent teacher evenings to decide on the grade. The school's principal, Donna Chambers, said that the scheme had been well received.

    “There were some critics. In spite of it, between 15 per cent and 20 per cent of parents started out in the lower categories but now that has been reduced to just two per cent,” she explained.

    Chambers hopes that the scheme will help motivate parental involvement. “The system is important because you have got to get the parents on board from day one. That one hour initial conversation saying they could improve will make a difference to the rest of that child's academic life”, she said.

    But while the scheme may be well intentioned, it is likely to be connected with parent shaming. There are lots of reasons why some mums and dads might not be involved in school activities such as work commitments, looking after younger children or caring for elderly relatives.

    And of course, being involved in your kid's education doesn't begin and end at school. There is a lot that goes on behind the scenes from helping with homework to keeping uniforms freshly laundered. And what about all the parents who stayed up sewing special costumes at the last minute? Surely that earns a gold star instead of a grade!

    Four years ago, we asked ourselves: what if we could create a shopping experience with no waiting in lines and no checkout? Or could we create a physical store where customers could simply take what they want and go? Our answer to those questions is Amazon Go, where you could experience the idea of "just walk out shopping".

    Amazon Go is a new kind of store with no checkout required. We created the world's most advanced shopping technology, so you never have to wait in line. With our "just walk out shopping" experience, simply use the Amazon Go app to enter the store, take the products you want, and go! No lines, no checkout.

    Our checkout-free shopping experience is made possible by the same types of technologies used in self-driving cars: computer vision, sensor fusion, and deep learning. Our "just walk out technology" automatically detects when products are taken from or returned to the shelves and keeps track of them in your virtual cart（虚拟购物车）. When you've done shopping, you can just leave the store. Shortly after, we'll charge your Amazon account and send you a receipt(收据).

    We offer delicious ready-to-eat breakfast, lunch, dinner, and snack options made fresh every day by our on-site chefs and favorite local kitchens and bakeries. Our selection of foodstuff ranges from bread and milk to cheeses and locally made chocolates. You'll find well-known brands we love, plus special finds we're excited to introduce to customers. For a quick home-cooked dinner, pick up one of our chef-designed Amazon Meal Kits, and you can make a meal for two in about 30 minutes.

    Our 1,800-square-foot shopping space is conveniently compact(紧凑的), so busy customers can get in and out fast. It is located at 2131, 7th Ave, Seattle, WA, on the corner of 7th Avenue and Blanchard Street. All you need is an Amazon account, a supported smartphone, and the free Amazon Go app.

    Amazon Go is currently only open to Amazon employees in our testing program, and will be open to the public soon.

    Language is always changing. In a society where life continues year after year with few changes, the language does not change either. The earliest known languages had difficult grammar but a small, limited vocabulary. Over the century, the grammar changed, and the vocabulary grew. For example, the English and Spanish people who came to America during the sixteenth century gave names to all the new plants and animals they found. In this way, hundreds of new words were introduced into English and Spanish vocabularies. Today life is changing very fast, and language is changing fast too.

     There are several major(主要) language families in the world. Some scientists say there are nine main families, but other scientists divide them differently. The languages in each family are connected, and scientists think that they came from the same parent language. About 3 percent of the people in the world speak languages that are not in these major families.

    Kaitlin Woolley and Ayelet Fishbach report in Psychological Science that a meal taken "family-style" from a central plate can greatly improve the outcome of later negotiations.

    Having conducted previous research in 2017 revealing that eating similar foods led to people feeling emotionally closer to one another, Dr Woolley and Dr Fishbach wondered whether the way in which food was served also had a psychological effect. They theorized that, on the one hand, sharing food with other people might indicate food scarcity（短缺）and increase a feeling of competition. However, they also reasoned that it could instead lead people to become more aware of others' needs and drive cooperative behavior as a result. Curious to find out, they did a series of experiments.

    For the first test they recruited 100 pairs of participants from a local cafe, none of whom knew each other. The participants were seated at a table and fed tortilla chips with salsa. Half the pairs were given their own basket of 20 grams of chips and a bowl of 25 grams of salsa, and half were given 40 grams of chips and 50 grams of salsa to share. As a cover for the experiment, all participants were told this snack was to be consumed before the game began.

    The game asked the participants to negotiate an hourly wage rate during a fictional strike. Each person was randomly assigned to represent the union or management and follow a set of rules.

    The researchers measured cooperation by noting the number of rounds it took to reach an agreement, and found that those who shared food resolved the strike significantly faster（in 8. 7rounds）than those who did not（13.2 rounds）. A similar experiment was conducted with 104

participants and Goldfish crackers（饼干）, this time negotiating an airline's route prices. The results were much the same, with the food-sharers negotiating successfully 63. 3%of the time and those who did not share doing so 42. 9%of the time.

    If you wear glasses, chances are you are smarter. Research published in the famous British journal Nature Communications has found that people who displayed higher levels of intelligence were almost 30 percent more likely to wear glasses.

    The scientists studied the genes of thousands of people between the ages of 16 and 102.The study showed intelligence can be connected to physical characteristics. One characteristic was eyesight. In out of 10 people who were more intelligent, there was a higher chance they needed glasses. Scientists also said being smarter has other benefits. It is connected to better health.

    It is important to remember these are connections which are not proven causes. Scientists call this correlation. Just because something is connected to something else does not mean one of those things caused the other. And it's worth noting that what constitutes intelligence is subjective and can be difficult, if not impossible, to measure.

    Forget genes though. Plenty of proof shows wearing glasses makes people think you are more intelligent, even if you do not need glasses. A number of studies have found people who wear glasses are seen as smarter, hard-working and honest. Many lawyers use this idea to help win their cases. Lawyer Harvey Solves explained this. Glasses soften their appearance. He said sometimes there has been a huge amount of proof showing that people he was defending broke the law. He had them wear glasses and they weren't found guilty.

    Glasses are also used to show someone is intelligent in movies and on TV. Ideas about people who wear glasses have begun to shift. People who do not need glasses sometimes wear them for fashion only. They want to look worldly or cool. But not everyone is impressed by this idea, though. GQ magazine said people who wear glasses for fashion are trying too hard to look smart and hip (时髦的). However, that hasn't stopped many celebrities from happily wearing glasses even if they do not need them. Justin Bieber is just one high-profile fan of fashion glasses.