If you don't use your arms or your legs for some time, they become weak; 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 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. But if he tells us that he has a poor memory, many of us think that his parents are to blame, 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 can not read or write and they have to remember things; they can not write down in a little notebook; they have to remember days, songs and stories; so their memory is the whole time being exercised. So if you want to have a good memory, learn from the people: practice remembering.

    Most heroes are not super. They don't appear in comic books, on television, or in movies. They just do what they believe needs to be done to make their world a better place. Bike Batman is one of them.

    Bike Batman is a 30-year-old married engineer who lives in Seattle, Washington. He's a cyclist who also buys and sells bikes as a hobby.

    About three years ago, he was looking for a bike for his wife. He found one on Craigslist, a website where people list things they want to sell. As he often does, he also looked at Bike Index, a popular website that allows users to register their bikes and post reports when they're taken. The bike, which he was considering purchasing, clearly matched one reported stolen on Bike Index. Then he called the person who claimed to be the bike's owner and arranged to meet him— supposedly to complete the sale. When the two men met, Bike Batman told the thief, "You've got two options. You can wait until a police officer gets here, or you can just get out of here." You can imagine what the thief did.

    After that first success, Bike Batman developed a safer routine. When he sees questionable bike ads on Craigslist, he cross-references the image with bikes reported on Bike Index. Once he has confirmed it with the owner, he arranges a meet-up with the thief and will call the Seattle police department so that officers can participate in the action. In more than half of the 22 cases in which he has got back and returned bikes, the thieves have been arrested. In one case, Bike Batman even helped a family recover a wide range of prized possessions that suspects had stolen during a home burglary.

    His nickname came from a discussion with a police officer who suggested he be called "Robin Hood". Since he wasn't exactly stealing from the rich and giving to the poor, "Batman" seemed a better fit. The idea of a superhero punishing criminals feels pretty silly to him, but the main reason he continues his work is to keep up Seattle's reputation as a friendly city.

    "Let's go see Santa!" Samantha said, pointing.

    I shrugged. I found out long ago that the real Santa doesn't hang out in malls. He's always too busy checking his list for kids twice and supervising the elves (小精灵).

    Last year, "Santa" had a tattoo on his arm. I pretended I didn't notice and named all the toys I ever wanted, until he was about to kick me out. I like playing around with fake Santas.

    We joined the line and after what seemed like ages, it was our turn. Samantha's eyes were glowing with excitement as she listed her wishes. She went back to Mom and Dad with a delighted smile and some candies.

    I sat on Santa's lap and moved from side to side to get comfortable. He made a face. "Have you been good this year? Ho! Ho!"

    "Oh, yes! I played nicely with my sister, obeyed my parents, and teachers are fond of me. "

    A suspicious smile appeared on his jolly face. "What would you like for Christmas, my boy?" "Santa, I want a new teacher for Christmas."

    He got a little surprised and looked at me. "Don't you want any new games, or a baseball mitt (手套)?"

    "No. I want a new teacher who doesn't give too much homework. I don't have time to play anyway, with all those assignments I'm getting. "

    It was worth waiting in line just to see the look on his face. He gave me a coloring book and a Christmas sticker. Just before I left, he pulled me closer and said in a low tone, "I'll make sure Miss Coleman makes your wish come true."

    How did he … that voice … "Mr. Principal?"

    I guess sometimes wishes do come true. I had a lighter workload until June!

    Robots are now being employed not just for dangerous tasks, such as discovering mines or rescuing people in disasters. They are also finding application as household helps and as nursing assistants. As increasing numbers of machines, equipped with the latest artificial intelligence, take on a growing variety of specialized and everyday tasks, the question of how people see them and behave towards them becomes ever more urgent.

    A team led by Sari Nijssen of Radboud University and Markus Paulus, Professor of Developmental Psychology at Ludwig-Maximilians-Universitaet (LMU), have carried out a study to determine the degree to which people show concern for robots and behave towards them based on moral principles.

    According to Sari Nijssen, the study set out to answer the following question:" Under what circumstances would adults be willing to sacrifice robots to save human lives?" The participants were faced with a hypothetical (假设的) moral dilemma: Would they be prepared to put a single person at risk in order to save a group of injured persons? In the situations presented the intended victim was either a human, a humanoid robot that had been humanized (人性化的) to various degrees or a robot that was clearly recognizable as a machine.

    The study suggested that the more the robot was humanized, the less likely participants were to sacrifice it. Situations that included vivid stories in which the robot was described as a merciful being or as a creature with its own understandings, experiences and thoughts, were more likely to stop the study participants from sacrificing it in the interests of anonymous (无名的) humans.

    "This result indicates that our study group attached a certain moral status to the robot," says Paulus. "One possible suggestion of this finding is that attempts to humanize robots should not go too far. Such efforts could come into conflict with their intended function—to be of help to us."

    Humans are social animals. They live in groups all over the world. As these groups of people live apart from other groups, over the years and centuries they develop their own habits and ideas, which are different from other cultures. One important particular side of every culture is how its people deal with time.

    Time is not very important in nonindustrial (非工业的) societies. The Nuer people of East Africa, for example, do not even have a word TIME that is in agreement with the abstract thing we call time. The daily lives of the people of such nonindustrial societies are likely to be patterned around their physical needs and natural events rather than around a time schedule (时间表) based on the clock. They cook and eat when they are hungry and sleep when the sun goes down. They plant crops during the growing seasons and harvest them when the crops are ripe. They measure time not by a clock or calendar, but by saying that an event takes place before or after some other event. Frequently such a society measures days in terms of "sleeps" or longer periods in terms of "moons". Some cultures, such as the Eskimos of Greenland measure seasons according to the migration of certain animals.

    Some cultures which do not have a written language or keep written records have developed interesting ways of "telling time". For example, when several Australian aborigines want to plan an event for a future time, one of them places a stone on a cliff or in a tree. Each day the angle of the sun changes slightly. In a few days, the rays of the sun strike the stone in a certain way. When this happens, the people see that the agreed-upon time has arrived and the event can take place.

    In contrast (成对比), exactly correct measurement of time is very important in modern, industrialized societies.

    This is because industrialized societies require the helpful efforts of many people in order to work. For a factory to work efficiently (well, quickly and without waste), for example, all of the workers must work at the same time. Therefore, they must know what time to start work in the morning and what time they may go home in the afternoon. Passengers must know the exact time that an airplane will arrive or depart. Students and teachers need to know when a class starts and ends. Stores must open on time in order to serve their customers. Complicated (复杂的) societies need clocks and calendars. Thus, we can see that if each person worked according to his or her own schedule, a complicated society could hardly work at all.

It was the early 1950s, and I was a member of the A class at Armidale Senior High School in norther New South Wales. 

In the second and third years we all did General Maths, and our teacher was Mrs Lindsay-Clare Lindsay. Her arrival at our classroom was always quick, "Good morning everyone!" Then our books would be out, and we would watch her closely. 

I've thought a lot about Clare Lindsay over the years. What was her special magic? There are two reasons and I think they're necessary for all excellent teachers. She loved her subject, and she loved us, in a patient and objective way. She had no favorites that I can remember, and she called us all by our first names pleasantly She had a way of teaching that I loved. 

"Now we could go down this path couldn't we? We could argue this, and then this, but that doesn't work because of this. No Can Do(NCD)!" She would put a big cross, and write" NCD" against what she had put down. "Right! Why not go down this new path?" And she would show us that this new way worked. It was fun. We, whether the poor students or the skilled, all did well because of her. I've never found maths difficult, and I_put_that_skill_down_to_her. 

In the fourth and fifth years,we were divided into the science and arts streams(按学生能力划分的班级), and Mrs Lindsay didn't teach us any more. But as the Leaving Certificate exams were coming, one of my friends became nervous about how much maths he didn't know. With great courage, he went to see Mrs Lindsay, and asked if she would help him prepare for his General Maths paper. "Of course!" she said, and did just that, after school, in her own time. He passed. What a good teacher!