Good afternoon, and welcome to England. We hope that your visit here will be a pleasant one. Today, I would draw your attention to a few of our laws.

    The first one is drinking. Now, you may not buy wine in this country if you are under 18 years of age, nor may your friends buy it for you.

    Secondly, noise. Enjoy yourselves by all means, but please don't make unnecessary noise, particularly, at night. We ask you to respect other people who may wish to be quiet.

    Thirdly, crossing the road. Be careful, the traffic moves on the left side of the road in this country. Use pedestrian crossing(人行横道) and don't take any chance when crossing the road.

    My next point is about rubbish. It isn't lawful to drop rubbish in the street. When you have something to throw away, please put it in your pocket and take it home, or put it in a dustbin.

    Finally, as regards smoking, it is against law to buy cigarettes or tobacco if you are under 16 years of age.

    I'd like to finish by saying that if you require any sort of help or assistance, you should contact the police, who will be pleased to help you. You can call, write or directly go to any policeman.

    Fighting racial stereotypes（模式化）on US campuses often begins by putting students of different ethnic backgrounds together — under one dormitory roof.

    Sam Boakye was a freshman at Ohio State University and the only black student on his floor. He was determined to get good grades — in part to make sure his white roommate had no basis for negative racial views. "You're pushed to do better, to challenge the stereotype that black people are not that smart," he told the New York Times.

    Several recent studies have found that having a roommate of a different race can reduce prejudice(偏见), diversify(使多样化) friendships and even promote students' academic performance. In a study by Ohio State psychology professor Russell Fazio, black freshmen who came to college with high test scores earned better grades if they had a white roommate—even if the roommate's test scores were low. Another study on student interaction by Duke University suggests that freshmen with roommates of a different race were the most likely to diversif“y their friendships. Just having diversity in classrooms doesn't do anything to increase interracial friendships," said Claudia Buchman, an author of the Duke study. “But living together with a different-race roommate does lead to more interracial friendships."

    There are, however, some problems with such room assignments. Fazio's study found that three times as many randomly(随机地) assigned interracial roommates weren't living together at the end of the semester, compared with white roommates. Interracial roommates also spent less time together, had fewer joint activities and were less involved with each other's friends than white pairs.

    As for Boakye, this is not the case. "A lot of white students come without much exposure（暴露）to diversity, so when their first interaction with a black guy isn't bad, they will make more black friends. I think I made a good impression on my freshman roommate. I saw him this year, and he said, "Hey dude, you're not the only black friend I have. That felt good."

    If you are a fruit grower—or would like to become one—take advantage of Apple Day to see what's around. It's called Apple Day but in practice it's more like Apple Month. The day itself is on October 21, but since it has caught on, events now spread out over most of October around Britain.

    Visiting an apple event is a good chance to see, and often taste，a wide variety of apples. To people who are used to the limited choice of apples such as Golden Delicious and Royal Gala in supermarkets, it can be quite an eye opener to see the range of classical apples still in existence, such as Decio which was grown by the Romans. Although it doesn't taste of anything special，it's still worth a try，as is the knobbly(多疙瘩的) Cat's Head which is more of a curiosity than anything else.

    There are also varieties developed to suit specific local conditions. One of the very best varieties for eating quality is Orleans Reinette, but you'll need a warm, sheltered place with perfect soil to grow it, so it's a pipe dream for most apple lovers who fall for it.

    At the events, you can meet expert growers and discuss which ones will best suit your conditions, and because these are family affairs, children are well catered for with apple­themed fun and games.

    Apple Days are being held at all sorts of places with an interest in fruit, including stately gardens and commercial orchards(果园)．If you want to have a real orchard experience, try visiting the National Fruit Collection at Brogdale，near Faversham in Kent.

    On Friday, Germany's telecom regulator(电信业管理者), the Federal Network Agency, announced that a number of children s smartwatches, designed for ages 5 to 12, can allow someone to remotely tap into the watch s microphone and secretly spy from remote places. The regulator isn't just worried about the potential of people spying on children-it's worried the devices(设备) can be used to spy on anyone.

    And in Germany, it's illegal to record private conversations without permission. "According to our investigations, parents were using the watches, for example, to listen in on their children during class, said Federal Network Agency President Jochen Homann in a statement.

    Smartwatches that make phone calls, like the Apple Watch, are legal in Germany. The problem with many of the children's smartwatches, however, is that the devices have a classic spying function, similar to a baby monitor, which can be easily activated (激活) just by using an app.

    The German regulator is so serious about destroying these devices. It's asking citizens to document the watches' destruction and file evidence online. Once the watches are destroyed, the regulator will provide a "certificate of destruction," confirming the deed was done.

    This isn't the first time the Federal Network Agency told German citizens to destroy a consumer device. The regulator once prohibited the doll "My Friend Cayla", which was fitted with radio transforming technology that could allow children to be spied on.

    Remind tech producers: The German government won't just ban devices that can spy on anyone, they'll demand the devices be destroyed with hammers (or whatever means of destruction one prefers) — even if they're dolls.

    Computers have beaten human world champions at chess and, earlier this year, the board game Go(围棋). So far, though, they have struggled at the card table. So we challenged one AI(artificial intelligence) to a game.

Why is poker so difficult? Chess and Go are “information complete” games where all players can see all the relevant information. In poker, other players' cards are hidden, making it an “information incomplete” game. Players have to guess opponents' hands from their actions—-tricky for computers. Solving poker could lead to many breakthroughs, from cyber security to driverless cars.

    Scientists believe it is only a matter of time before AI once again vanquishes humans, so our human-machine match comes up in a game of Texas Hold's Em Limit Poker. The AI was developed by Johannes Heinrich, a researcher studying machine learning at UCL. It combines two techniques: neural(神经的)networks and reinforcement learning(强化学习).

    Neural networks, to some degree, copy the structure of human brains: their processors are highly interconnected and work at the same time to solve problems. They are good at spotting patterns in huge amounts of data. Reinforcement learning is when a machine, given a task, carries it out, learning from mistakes it makes. In this case, it means playing poker against itself billions of times to get better.

    Mr Heinrich told Sky News: “Today we are presenting a new procedure that has learned in a different way, more similar to how humans learn. In particular, it is able to learn abstract patterns, represented by its neural network, which allow it to deal with new and unseen situations.”

    After two hours of quite defensive play, from the computer at least, we called it a draw.

    City trees grow faster and die younger than trees in rural forestry, a new study finds. Over their lifetimes, then, urban trees will likely absorb less CO₂ from the air thah forest trees.

    As we all know, the earth would be freezing or burning hot without CO₂. However, CO₂ is a greenhouse gas, meaning it traps energy from the sun as/heat. That makes temperatures near the ground rise. Human activities, especially the widespread burning-of fossil(化石)fuels, have been sending extra greenhouse gases into the air. This has led to a rise in average temperatures across the globe.

    Studies had shown forests readily absorb CO₂, but there hadn't been much data on whether city trees grow, die and absorb CO₂ at the same rate as forest trees do. So some researchers decided to find out.

    To figure out how quickly trees were growing, researchers tracked their diameters (the width of their trunks) between 2005 and 2014. A tree's diameter increases as it grows, just as a person's waist size increases as they gain weight. About half the weight of a tree is carbon, research has shown. Most of the rest is water. Over the nine years' tracking, the researchers found city trees absorbed four times as much carbon from the air as forest trees. However, they were twice as likely to die. So over the lifetime of each type of tree, forest trees actually absorbed more CO₂.

    City trees grew faster because they had less competition for light from their neighbors. In a forest, trees tend to grow close together, shading their neighbors. Street trees also benefit from higher levels of nitrogen (氮)in rainwater. Nitrogen helps plants grow. Waste gases from gas-burning cars also contain nitrogen, thus enriching city air with nitrogen. Later, rainwater may wash much of it to the ground. Some street trees may also have better access to water than trees in the country because the underground water pipes can leak.