In the last few years the popularity of eBooks has exploded．The advantages are clear：You can carry as many books with you as you want．You can simply download every book you like and instantly start reading instead of having to wait for the book to arrive by mail．

    However，one thing hadn't changed．If you wanted to rent a book you were still forced to use hardcopy books．Until now that is, Amazon．com recently announced the start of a new program where you can rent eBooks．

Where to rent eBooks？

    As mentioned before，Amazon．com is the first and currently the only retailer (零售商) that has a program in place for renting eBooks． Luckily，Amazon is the largest online retailer in the world and their eBook assortment (分类) is massive．They are also the producer of the Kindle，the most popular Reader，which means you can be sure that the eBooks you rent will work．

You can currently only rent Textbooks．But this is likely to change as soon as word gets out that you can save money by renting eBooks.

Why rent eBooks at Amazon?

* Save money：Save up to 80% of the normal price of the eBook．

* Decide how long you rent：From 30 days to 360 days，you decide how long you want it．You can extend the time by as little as a day．Or simply buy the eBook if you want to keep it after all．

*Use any device：If you rent an eBook from Amazon，you can read it on your PC，Mac，iPad，iPhone，Android device，Windows Phone 7．Blackberry．or Kindle．

* Keep your notes：Do you like to keep annotations (注释) and highlights in your eBooks？Don't worry．You can always revisit your notes and highlights through Amazon．com．

How to rent eBooks？

    Simply search for the eBook you want to rent on Amazon．com and select the "Rent eBooks" option. After that，a new page will open where you can select how long you'd like to rent the eBook．You can read eBooks for a period of 30 to 360 days．

    You decide how long you need the eBook．If you later find out you need it for longer, you can simply extend the time．Or buy it for the normal price whenever you want.

    Once you've chosen the time you want to rent the eBook，you simply go to checkout．Or you can use the "Rent now" button．

    In the late 1990s, Google was just a start-up company operating out of a garage in PaloAlto, California. Co-founders Larry Page and Sergey Brin started the company while studying at Stanford University. Google's founders and its employees, then understood some of the challenges that entrepreneurs(创业者) around the world may face. An entrepreneur is a person who starts a business. They must be willing to risk financial loss in order to make money.

    Mary Grove is the director of a program called Google for Entrepreneurs. She said Google wants to help new start-up businesses grow and be successful.

Google for Entrepreneurs has opened campuses around the world. Entrepreneurs in each city can use Google's

    buildings without paying.Entrepreneurs can work with each other and learn from people who are more experienced in business.

    Yeram Kwon is the head of a company in South Korea.Her business is called L.M.Lab. It makes a product that helps people learn to perform the lifesaving technique called CPR. She said she has learned how to solve some of her business problems by attending Google events in Seoul.

    Outside of its own buildings in these cities, Google provides financial support and resources for partner organizations around the world. Building partnerships is a way for Google to spread the idea of entrepreneurialism around the world. Google can use its network to help find people who want to invest in start-up businesses. Those people need to be ready to take risks. That is something Kwon said that makes some Koreans uncomfortable. "Most

    Korean people think that it is much safer to work for big companies like Samsung and LG," she said. But, Kwon said the Korean government and technology companies are now supporting people willing to take business risks.

    One advantage of the Internet is shopping conveniently online for clothes; one disadvantage of the Internet is also shopping conveniently online for clothes.

    "Nothing fits," said Lam Yuk Wong, a senior in electrical and computer engineering at Rice University. "Everyone says this. They order clothes and they don't fit. People get very unhappy."

    Wong and her design partner, Xuaner "Cecilia" Zhang, are Team White Mirror, creators of what they call a "virtual (虚拟)fitting room". Their goal is simple and consumer-friendly: to let online clothing shoppers have a perfect fit and a perfect look when shopping every time. Both women are from China, Wong from Hong Kong and Zhang from Beijing. They both order most of their clothing online. They got the idea from their own experience as consumers and from listening to the complaints of friends and relatives. "They say, 'The color is wrong' or 'I got the right size but it still does not fit.' We want to make it like you're in the store trying on the clothes," Zhang said.

    Using a Kinect developed by Microsoft for use with its Xbox 360 video game player, Zhang scans Wong and turns her image into, in effect, a virtual model, keeping Wong's dimensions (尺寸), and even her skin and hair color. "We put the clothes on the shopper's 3-D body models and show how they look when they are dressed," Wong said. So far, Wong and Zhang have adapted the software to show dresses and shirts, and they are now working on shorts.

    Asked if she thought men as well as women might be interested in using their virtual fitting room, Wong said, "I think their wives will care about this, so it will also be important to men."

    As my dad unwrapped（打开）the new bicycle helmet（头盔）that I got him for his birthday, I realized that a number of people ride their bicycles every day without the protection of a helmet.

      Due to cold winters across the country, riding has become increasingly dangerous as many roads have holes and are torn-up（磨损的）. Not everyone realizes that there are laws requiring the wearing of helmets in many places.

    Where I live, there has been a law in place since October 1, 1992 stating that cyclists of all ages are required to wear helmets. Unfortunately, accidents can happen to the best of riders. My dad has been a cyclist for many years, and he often rides around my county and to Rockland Lake State Park.

    One afternoon, as he was just entering the park, he lost control of his bicycle and flew off and landed on a nearby patch of grass, breaking his helmet into pieces and losing consciousness（知觉）. When he was just awakening, a lovely couple found him and brought him back to our house, where he attempted to recall the events leading up to his fall. Later that day, a CAT scan showed that he had a concussion (脑震荡). That evening, while my dad was showing me the pieces of his broken helmet, we both came to a shocking realization.

    If he had not worn his helmet, he probably would have cracked his skull and perhaps died. Today, when my dad and I go out cycling, the wearing of our helmets is not even a question. Regardless of age, everyone should wear a helmet whenever they get on a bicycle.

    Pyramid of Giza

    One of seven wonders of ancient world also becomes favorite site for astronomers to capture photographs from the orbit. It is not at all visible with naked eyes from space, so astronomers used special cameras for it.

    Grand Canyon

    It surely takes many days to enjoy every site of 277-mile-long Grand Canyon in Arizona. But the astronauts at orbits of Earth are able to see Grand Canyon with their own eyes all at once. The space images of Grand Canyon help the scientists to make surface map of the steep sided Canyon, also to monitor the changes within its surface.

    Ganges River Delta

    Ganges River Delta is 220 miles long; this amazing geographic feature can also seen from orbits of Earth. When the river becomes empty, it becomes the largest remaining habitat of Bengal tiger and other rich wild life.

    Palm Island, Dubai

    Palm Island along with world islands of Dubai can be seen even from space. The Palm Island actually holds two artificial island in shape of palm tree, spreading across in an area of 100,000 square meters. You can meet hundreds of luxury hotels and parks within this man-made wonder.

    It's common knowledge that the woman in Leonardo da Vinci's most famous painting seems to look back at observers, following them with her eyes no matter where they stand in the room. But this common knowledge turns out wrong.

    A new study finds that the woman in the painting is actually looking out at an angle that's 15.4 degrees off to the observer's right­well outside of the range that people normally believe when they think someone is looking right at them. In other words, said the study author, Horstmann, "She's not looking at you." This is somewhat ironic, because the entire phenomenon of a person's gaze (凝视) in a photograph or painting seeming to follow the viewer is called the "Mona Lisa effect" . That effect is absolutely real, Horstmann said. If a person is illustrated or photographed looking straight ahead, even people viewing the portrait from an angle will feel they are being looked at. As long as the angle of the person's gaze is no more than about 5 degrees off to either side, the Mona Lisa effect occurs.

    This is important for human interaction with on-screen characters. If you want someone off to the right side of a room to feel that a person on-screen is looking at him or her, you don't cut the gaze of the character to that side­surprisingly, doing so would make an observer feel like the character isn't looking at anyone in the room at all. Instead, you keep the gaze straight ahead.

    Horstmann and his co-author were studying this effect for its application in the creation of artificial-intelligence avatars(虚拟头像) when Horstmann took a long look at the "Mona Lisa" and realized she wasn't looking at him.

    To make sure it wasn't just him, the researchers asked 24 people to view images of the "Mona Lisa" on a computer screen. They set a ruler between the viewer and the screen and asked the participants to note which number on the ruler intersected Mona Lisa's gaze. To calculate the angle of Mona Lisa's gaze as she looked at the viewer, they moved the ruler farther from or closer to the screen during the study. Consistently, the researchers found, participants judged that the woman in the "Mona Lisa" portrait was not looking straight at them, but slightly off to their right.

    So why do people repeat the belief that her eyes seem to follow the viewer? Horstmann isn't sure. It's possible, he said, that people have the desire to be looked at, so they think the woman is looking straight at them. Or maybe the people who first coined the term "Mona Lisa effect" just thought it was a cool name.