What will power your house in the future？Nuclear, wind, or solar power？According toscientists at the Massachusetts Institute of Technology(MIT)in the US, it might beleaves—but artificial(人造的)ones.

    Natural leaves are able to change sunlight and water intoenergy. It is known as photosynthesis(光合作用). Nowresearchers have found a way to imitate this seemingly simple process.

    The artificial leaf developed by Daniel Nocera and hiscolleagues at MIT can be seen as a special silicon chip with catalysts(催化剂). Similar tonatural leaves, it can splitwater into hydrogen and oxygen when put into a bucket of water. The hydrogenand oxygen gases are then stored in a fuel cell, which usesthose two materials to produce electricity, located eitheron top of a house or beside the house.

Though the leaf is only about the shape of a poker card, scientistsclaimed that it is promising to be an inexpensive source of electricity indeveloping countries.“ One can imagine villages in India and Africa not longfrom now purchasing an affordable basic power system based on this technology, ”said Noceraat a conference of the American Chemical Society.

    The artificial leaf is not a new idea. The first artificial leafwas invented in 1997 but was too expensive and unstable for practical use. Thenew leaf, by contrast, is made ofcheap materials, easy to useand highly stable. In laboratory studies, Nocera showedthat an artificial leaf prototype(原型)could operatecontinuously for at least 45 hours without a drop in activity.

    The wonderful improvements come from Nocera's recent discoveryof several powerful, new andinexpensive catalysts. These catalysts make the energy transformation insidethe leaf more efficient with water and sunlight. Right now, the new leafis about 10 times more efficient at carrying out photosynthesis than a naturalone. Besides, the device canrun in whatever water is available；that is, it doesn'tneed pure water. This is important for some countries that don't have access topure water.

    With the goal to “make each home its own power station” and“give energy to the poor”, scientistsbelieve that the new technology could be widely used in developing countries, especially inIndia and rural China.

Evolution.

In 1978, I was 18 and was working as a nurse in a small town about 270 km away from Sydney, Australia. I was looking forward to having five fays off from duty. Unfortunately, the only one train a day back to my home in Sydney had already left. So I thought I'd hitch a ride (搭便车).

I waited by the side of the highway for three hours but no one stopped for me. Finally, a man walked over and introduced himself as Gordon. He said that although he couldn't give me a lift, I should come back to his house for lunch. He noticed me standing for hours in the November heat and thought I must be hungry. I was doubtful as a young girl but he assured (使……放心)me I was safe, and he also offered to help me find a lift home afterwards. When we arrived at his house, he made us sandwiches. After lunch, he helped me find a lift home.

Twenty-five years later, in 2003, while I was driving to a nearby town one day, I saw an elderly man standing in the glaring heat, trying to hitch a ride. I thought it was another chance to repay someone for the favour I'd been given decades earlier. I pulled over and picked him up. I made him comfortable on the back seat and offered him some water.

After a few moments of small talk, the man said to me, “You haven't changed a bit, even your red hair is still the same.” I couldn't remember where I'd met him. He then told me he was the man who had given me lunch and helped me find a lift all those years ago. It was Gordon.

    Spring is a wonderful season to celebrate rebirth and new life. The long, cold winter is over. The weather is warmer and sunnier. The trees again have leaves and the flowers are blooming. The season represents hope, joy and beauty. At this time, many people think of this classical music piece—Spring, which shows happiness. Italian composer Antonio Vivaldi wrote it in the seventeen hundreds.

    However, not all songs about spring are happy. This song written and sung by K.D. Lang is about dreaming of spring in cold dark places. She recorded I Dream of Spring in 2008.

    Richard Rodgers and Oscar Hammerstein wrote It Might as Well Be Spring for the movie State Fair in 1945.Frank Sinatra sings it. It is a feeling of restlessness or excitement brought on by the coming of spring. Richard Rodgers also wrote Spring Is Here, this time with Lorenz Hart. Ella Fitzgerald sings this song about feeling lonely during this season.

    Frank Loesser wrote the sad song, Spring Will Be a Little Late This Year. Why has the season been delayed? Because the singer's lover has left her. Sarah Vaughn released(发行) her version of the song in 1953.

    By now you may be thinking, "Enough with the sad songs, already！"OK ,then how about a cowboy song? Gene Autry was one of the America's most famous singing cowboys. He recorded When It's Spring time in the Rockies in 1937.

    And finally, we'll leave you with a sunny song called Up Jumped Spring. Freddie Hubbard wrote this jazz song in 1977 and Billy Taylor Trio performs it.

    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.

    Sometimes people add to what they say even when they don't talk. Gestures are the "silent language" of every culture. We point a finger or move another part of the body to show what we want to say. It is important to know the body language of every country or we may be misunderstood.

    In the USA, people greet each other with a handshake in a formal introduction. The handshake must be firm. If the handshake is weak, it is a sign of weakness or unfriendliness. Friends may place a hand on the other's arm or shoulder. Some people, usually women, greet a friend with a hug.

    Space is important to Americans. When two people talk to each other, they usually stand about two and a half feet away and at an angle (角度), so they are not facing each other directly. Americans get uncomfortable when a person stands too close. They will move back to have their space. If Americans touch another person by accident, they say, "Pardon me" or "Excuse me". Americans like to look at the other person in the eyes when they are talking. If you don't do so, it means you are bored, hiding something, or are not interested. But when you stare at someone, it is not polite.

    For Americans, thumbs-up means yes, very good, or well done. Thumbs-down means the opposite. To call a waiter, raise one hand to head level or above. To show you want the check, make a movement with your hands as if you are signing a piece of paper. It is all right to point at things but not at people with the hand and index finger (食指). Americans shake their index finger at children when they scold them and pat them on the head when they admire them.

    Learning a culture's body language is sometimes confusing. If you don't know what to do, the safest thing to do is to smile.

    Roughly the size of a soda can, sitting on a bookshelf, a relatively harmless device(设备) may be turning friends away from your home. The elephant in your living room is your Internet-connected camera, a device people are increasingly using for peace of mind in their homes. But few stop to think about the effect these devices may have on house guests. Should you tell your friends, for instance, that they're being recorded while you all watch the big game together?

    "It's certainly new territory, especially as home security cameras become easier to fix," says Lizzie Post, president of the Emily Post Institute, America's distinguished manners advisors." I think it will be very interesting to see what manners appear in terms of whether you tell people you have a camera or not, and whether guests have a right to ask that it be turned off, if it's not a security issue. "Post wants to make clear that she's not talking about legal rights, but rather personal preference.

When it comes to security cameras, Post says it's a host's responsibility to make sure guests feel comfortable within their home. If the host casually acknowledges that there is a camera in the room by telling a story about it, that may be enough to provide an opening for a guest to say if they are uncomfortable.

    However, if a contractor(合约工)is working in your home, you don't need to tell them that there are cameras watching. Then again, the camera can also work in contractors' favor. "If anything does go wrong while they're in the house, they don't want to be blamed for it," she says. "In fact, the camera could be the thing that proves that they didn't steal the $20, or knock the vase off the table.