Before the invention of hair dryer,vacuum cleaners were being used for the purpose of drying and styling hair. The early vacuum cleaners could draw in air as well as blowing air.So,towards the end of the 19^th century,women used to dry their hair by using a vacuum cleaner.

    In 1890,a French salon owner Alexander F.Godefroy invented the first hair dryer.It blew warm air.However,it was not widely used,mainly because of its large size.

    The first convenient hand-held hair dryer used at home came up in 1920.It weighed over 2 lbs.However,it only produced 100 watts of power,which was not enough to dry the hair.After almost ten years came the gas-heated dryers that were widely used in barber shops.However,these dryers produced heat that was harmful to hair and the air from them made people sick,so they were soon gone.

    Around the 1940s and 1950s,the helmet（头盔）style electric dryers came into being.Curly hairstyles were popular during that time.Therefore,women used curlers and sat under the dryers to set their curls.Later,the curly style began to drop,and so did the popularity of the helmet style electric dryer.

    In the late 1950s,the first workable hair dryer was made.It had a hand-held dryer.It used only 300-400 watts. Ever since the 1950s,hand-held dryers have experienced many changes,in order to become quieter,lighter and smaller.However,how it works largely remains the same.The modem technology has made improvements to the hair dryer,reducing the heat damage to a person's hair.For producing shinier,smoother and healthier hair,dryers have been included with negative ion（负离子）technology that dries hair faster and with less heat.

    I've loved my mother's desk since I was just tall enough to see above the top of it as Mother sat doing letters. Standing by her chair, looking at the ink bottle, pens, and white paper, I decided that the act of writing must be the most wonderful thing in the world.

    Years later, during her final illness, Mother kept different things for my sister and brother. “But the desk,” she said again, “is for Elizabeth.”

    I never saw her angry, never saw her cry, I knew she loved me; she showed it in action. But as a young girl, I wanted heart-to-heart talks between mother and daughter. It never happened. And a gulf opened between us. I was “too emotional”. But she lived “on the surface”. As years passed and I had my own family, I loved my mother and thanked her for our happy family. I wrote to her in careful words and asked her to let me know in any way if she chose that she did forgive me. I posted the letter and waited for her answer. None came. My hope turned to disappointment, then little interest and, finally, peace—it seemed that nothing happened. I couldn't be sure the letter had even got to Mother. I only knew that I had written it, and I could stop trying to make her into someone she was not.

    Now the present of her desk told me, as she'd never been able to, that she was pleased that writing was my chosen work. I cleaned the desk carefully and found some papers inside—a photo of my father and a one-page letter folded and refolded many times. She had given me an answer in a way she chose. Mother, you always chose the act that speaks louder than words.

    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.

    Plan on traveling around the USA this summer? If you need help in arranging the trip, or want ideas about where to go and what to do, there are a number of outstanding websites that can make your American dream come true.

    Antarctica's ice white environment is going green and facing other unexpected threats. Scientists say that as temperatures go up in the polar area, invading (入侵) plants and insects, including the flies, cause a major threat.

More and more of these invaders, in the form of larvae(幼虫) or seeds, are surviving in coastal areas around the South Pole, where the temperature has risen by more than 3℃ over the past three decades. Glaciers have melted, exposing more land which has been occupied by mosses that have been found to be growing more quickly and thickly than ever before—providing potential green homes for invaders.

    “The common house flies are a perfect example of the problem the Antarctic now faces from invading species,” said Dominic Hodgson of the British Antarctic Survey. “It comes in on ships, where it exists in kitchens and then at bases on the continent. It now has an increasing chance of surviving in the Antarctic as it warms up, and that is a worry. Insects like the house flies carry bacteria that could have a deadly effect on native lifeforms.”

    The Antarctic has several native species of insects. Together with its native mosses these are now coming under increased threat from three major sources: visiting scientists increasing numbers of tourists and global warming. However, it is global warming that is the main driver of the greening of Antarctica.

    In 2015, more than 38, 000 tourists visited Antarctica. “These tourists are often very careful about not leaving waste or having mud. But they could carry seeds or larvae on their boots when they set foot on the Antarctic, “ said Hodgson.

    More and more invasive insects and plants have been found on the Antarctic and have required removal. “The insects and plants that are native to Antarctica have survived there for thousands of years,” said Hodgson, “We have got to act now if we want to save the environment.”

    There were smiling children all the way. Clearly they knew at what time the train passed their homes and they made it their business to stand along the railway, wave to complete strangers and cheer them up as they rushed towards Penang. Often whole families stood outside their homes and waved and smiled as if those on the trains were their favorite relatives. This is the simple village people of Malaysia. I was moved.

    I had always traveled to Malaysia by plane or car, so this was the first time I was on a train. I did not particularly(特别) relish the long train journey and had brought along many magazines to read and reread. I looked about the train. There was not one familiar face. I sighed and sat down to read my Economics.

    It was not long before the train was across the Causeway and in Malaysia. Johor Bahru was just a city like Singapore, so I was tired of looking at the crowds of people as they hurried past. As we went beyond the city, I watched the straight rows of rubber trees and miles and miles of green. Then the first village came into sight. Immediately I came alive, I decided to wave back.

    From then on, my journey became interesting. I threw my magazines into the waste basket and decided to join in Malaysian life. Then everything came alive. The mountains seemed to speak to me. Even the trees were smiling. I stared at everything as if I was looking at it for the first time.

    The day passed fast and I even forgot to have my lunch until I felt hungry. I looked at my watch and was surprised that it was 3:00 pm. Soon the train pulled up at Butterworth. I looked at the people all round me. They all looked beautiful. When my uncle arrived with a smile, I threw my arms around him to give him a warm hug. I had never done this before. He seemed surprised and then his weather-beaten face warmed up with a huge smile. We walked arm in arm to his car.

    I looked forward to the return journey.