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

    Why is poker(扑克) 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. Poker has become a new benchmark for AI research. 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, hence our human-machine match comes up in a game of Texas Hold's Em Limit Poker. The AI was developed by Johannes Heinrich, 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.

    When seeing the doctor, you feel better to know you will get some medicine. But the doctor knows that medicine is not always needed. Sometimes all a sick person needs is some reassurance (安想) that all will be well. In such cases the doctor may prescribe a placebo.

    A placebo is a sugar pill, a harmless shot, or an empty capsule. The patient thinks it is medicine and begins to get better. How does this happen?

    The study of the placebo opens up new knowledge about the way the human body can heal itself. It is as if there was a doctor in each of us. The doctor will heal the body for us if we let it. But it is not yet known just how the placebo works to heal the body. Some people say it works because the human mind fools itself. These people say that if the mind is fooled into thinking it got medicine, then it will act as if it did, and the body will feel better.

    Placebos don't always work. The success of this treatment seems to rest a lot with the relationship between the patient and the doctor. If the patient has lots of trust in the doctor and if the doctor really wants to help the patient, then the placebo is more likely to work. So in a way, the doctor is the most powerful placebo of all.

    A placebo can also have bad effects. If patients expect a bad reaction to medicine, then they'll also show a bad reaction to the placebo. Some doctors still think that if the placebo can have bad effects it should never be used. They think there is still not enough known about it.

    The strange power of the placebo does seem to suggest that the human mind is stronger than we think it is. There are people who say you can heal your body by using your mind. And the interesting thing is that even people who swear this is not possible have been healed by a placebo.

阅读下列短文，从每题所给的四个选项 （A 、B 、C  和 D ）中，选出最佳选项。

    Christmastime in the city brings forests of trees already cut and waiting to be sold. But some people like to drive to tree farms. Others wait for their trees to come to them. They order one from the pages of a catalog or on the Internet. Some say the easiest thing of all is to buy a man­made tree with Christmas lights already on it. No falling needles to have to clean up.

    The National Christmas Tree Association says 33,000,000 real trees were sold last year, compared to 9,000,000 man­made ones. Man­made trees generally cost more, but they can be reused. Most natural trees are cut up and recycled, but some people buy trees that can be planted.

    Most Christmas trees are now grown on farms instead of in forests. Twenty-one thousand tree farmers in the United States grow Christmas trees on more than 180,000 hectares. Oregon was the leading producer last year.

    Twenty-two percent of people who bought real trees last year chose them at a farm. Two percent of those people cut the trees themselves. The next most popular places were big stores like Walmart and Home Depot. Groups like the Boy Scouts also sell Christmas trees. But some people pay nothing for theirs. They steal it.

    Cornell University in Ithaca, New York, has many pretty evergreens. Some years ago, a university worker found a way to keep them there. A month before Christmas, workers treated them with “pink ugly mix”. It contains water and red food colour. The bright colour starts to disappear after about a month. It can take longer, however. Cornell decided not to use the mix this year, but the idea has spread.

    The summer before my dad died, we moved house. Up until that point, our family had our own space to spread out. Money was tight, so there was no television set, but we owned a turntable on which my dad's records played constantly. Mostly, it played Bob Dylan. Tracks from The Basement Tapes and Desire became an important part of our new life. My brother and I, aged 8 and 10，climbed trees, built hideaways and learned the words of Clothes Line Saga. We would chant over and over, lost in our own joy.

    It was January when my dad left us forever because of the cancer. He was 36 going on 37 then, the same age as Dylan. Afterwards, our laughter disappeared, but we kept on playing the records, which became our only ritual of remembrance. The two men became so intertwined in my head, I struggled to tell them apart.

    Dylan was my dad's gift to me. What child wouldn't be fascinated by songs full of pirates and seasick sailors? How did it feel to have No direction home? Farewell, Angelina became my party-piece. I would sing this at church cheese and wines to the assembled audience. A lot of donations were made.

    Growing up, I remained a fan of the music, but I wasn't obsessed with Dylan until one day in early 1995, my brother bought us both tickets to see him play at Brixton Academy. London felt like a long way to go. But finally seeing Dylan step out on to the stage brought a sudden rush of excitement.

    I have seen Dylan a couple of times since. My brother is not around so much these days. But he was up for a visit recently. We passed a happy evening laughing and drinking, while his son, aged nine, performed his party—piece Subterranean Homesick Blues for us. He sang it word-perfect. And so it goes on: Dylan's music as a gift, passed down the generations.

    Attractions in New York

    Empire State Building

    Towering over 444 meters into the sky, the building has an indoor and outdoor observation deck on the 86th and 102nd floor, where you can see the overall view of the New York City. The building houses more than 1000 businesses. You can buy your ticket online in advance to avoid waiting .Telephone ： 212-736-3100 Location ： 350 5th Avenue, New York, NY 10118.

    Open Hours： 08:00-02:00

    Central Park

    For more than 150 years, visitors have come to Central Park's 843 green acres in the heart of Manhattan. Since 1980, the Park has been managed by the Central Park Conservancy, in partnership with the public. You can visit the official website of Central Park to learn more about Park happenings and activities and to learn how to help Central Park Telephone： 212-310-6600

    Location: 59th to 110th Street, Manhattan Borough from Central Park West to 5th Avenue, New York

    City NY 10022

    Open Hours： 06:00-23:00

    The National 9/11 Memorial & Museum

    The National 9/11 Memorial & Museum is a place of remembrance honoring those who lost their lives in the terrorist attacks of September 11, 2001. The 9/11 Memorial Museum displays Monumental artifacts linked to the events of 9/11, while presenting stories of loss, sympathy and recovery that are central to telling the story of the 2001 attacks and the consequence. It also explores the global impact of 9/11 and its continuing significance.

    Telephone： 212-312-8800

    Location: 180 Greenwich St. World Trade Center New York City, NY 10007

    Open Hours： 09:00-20:00

    The Metropolitan Museum of Art

    At New York City's most visited museum and attraction, you will experience over 5,000 years of art from around the world. The Met is for anyone as a source of inspiration, and understanding. You can learn, escape, play, dream, discover and connect.

    Telephone： 212-535-7710

    Location ： 1000 5th Avenue, New York City, NY 10028-0198 Open Hours： 10:00-17:30

    Food Parts You Should Never Throw Away in the Garbage

    Pineapple Core (果心)

    When you carve out the core of t pineapple, don't throw it in the garbage. You can use the pineapple core for all kinds of recipes, and there are tons of vitamins and  minerals hiding within.To use the pineapple core: cut it and add it to fruit salad, put it into smoothies (水果雪泥), cut it into cubes and freeze for law use, or simply add it to water or even tea to improve flavor.

    Kiwi Skln

    If you never thought you could eat kiwi in the way you eat a peach, think again. That skin really is good for you and contains a lot of vitamin C, and in fact, it's also higher hi fiber than the rest of the fruit. Of course, that rough, ugly skin isn't for everyone, so if you don't like it, try adding a whole kiwi to a smoothie to hide the taste of the skin.

    Banana Peel

    Most of us eat the banana without giving the soft peel a second thought. Here's why that's a mistake: banana peel contains tryptophan (色氨酸), which increases "the happiness hormone" to help with mood regulation and nerve system. There are a few creative ways to use the peel. Cook or boil for at least 10 minutes to soften. You can add it to smoothies, stir-fries, or soups. And, for a treat, simply slice and bake a banana with the skin on.

    Water melon Skin and Seeds

    The delicious, red inside makes for a refreshing snack or juice, but you're able to get some powerful nutrients in the skin and seeds as well. Cut out the white part under the green outside and use it in your cooking. It has vitamin C and B6, to keep you healthy. As for the seeds, you can roast them in the oven. Then add them to salads or to nut snacks.