If you've been to Europe a few times already, chances are that you've hit all the big destinations: London, Paris, Rome,Berlin.On your next trip you can either visit those same cities a second time,or instead you can take a chance and walk the streets of some cities that are a little bit smaller,a little bit less famous,but still full of European grace and charm.Here are four European cities to visit that you probably haven't been to yet.

    Besancon,France

    This hidden French city has had a long reputation for being a well-kept secret.It can be at once sleepy with few tourists but abundant galleries,restaurants,and a wonderful Beaux Arts museum whose collection is second only to the Louvre.The city is wound by the River Doubs and also touts (吹捧) its own UNESCO World Heritage Site in the Citadel,home to several small museums and a zoo.

    Seville,Spain

    For the tourist who is already tired of Barcelona and Madrid,Seville offers a different take (意见) on Spain. Located on the Southern coast,it keeps beautiful signs of the long period of Moorish rule,nowhere more than in the Alcázar palace building,just one of the city's UNESCO World Heritage Sites.Seville has over a dozen museums, tropical parkland,and probably the best tapas (餐前小吃) culture in all of Spain.

    Ghent,Belgium

    Ghent is a city that looks like it should be the setting for a fairy tale. All of the typical Belgium features abound here-waffles and beer.Every year from Saturday before July 21,Ghent hosts a ten-day festival.This music and theater festival draws almost 2 million visitors,as the city streets transform into performance spaces for performers,buskers (街头艺人) and musicians.

    Palermo,Italy

    Palermo is the capital city of Sicily,the southern island off the coast of mainland Italy.The city has an ancient history,and the various cultures that have controlled the island through the years have all left their marks on it. You can see winding street markets,antique (古玩) fairs,and open air nightclubs here.

    While Jennifer was at home taking an online exam for her business law class, a monitor a few hundred miles away was watching her every move.

    Using a web camera equipped in Jennifer's Los Angeles apartment, the monitor in Phoenix tracked how frequently her eyes moved from the computer screen and listened for the secret sounds of a possible helper in the room. Her Internet access was locked－remotely－to prevent Internet searches, and her typing style was analyzed to make sure she was who she said she was: Did she enter her student number at the same speed as she had in the past? Or was she slowing down?

    In the battle against cheating，this is the cutting_edge and a key to encourage honesty in the booming field of online education. The technology gives trust to the entire system，to the institution and to online education in general. Only with solid measures against cheating, experts say, can Internet universities show that their exams and diplomas are valid—that students haven't just searched the Internet to get the right answers.

    Although online classes have existed for more than a decade, the concern over cheating has become sharper in the last year with the growth of “open online courses.” Private colleges, public universities and corporations are jumping into the online education field. Spending millions of dollars to attract potential students, while also taking steps to help guarantee honesty at a distance.

    Aside from the web cameras, a number of other high-tech methods are becoming increasingly popular. Among them are programs that check students' identities using personal information, such as the telephone numbers they once used.

    Other programs can produce unique exams by drawing on a large list of questions and can recognize possible cheaters by analyzing whether difficult test questions are answered at the same speed as easy ones. As in many university classes, term papers are scanned against some large Internet data banks for cheating.

    Considering that Sundarbans National Park is situated in thetropics, Septemberto March is the ideal time to come here. April, May and June are too hot while July andAugust often bring heavy season winds that limit travel and don't make for avery pleasant sightseeing experience. You can really enjoy doing lots ofcharming things in the Sundarbans during September to March.

    Take a river tour

    Most tourists who explore the Sundarbans arrive in KhulnaCity first. Fromthere, youcan join a boat tour that travels south along the Ganges River through miles ofpreserved forest all the way to Kotka, where there is a beautiful beach alongthe Bay of Bengal.

    Visit a bird habitat

    This bird habitat is a nesting place for dozens of tropicalbirds found in the Sundarbans. The best way to observe these birds isclimbing up the Sajnekhali Watchtower. If you're lucky, you'll also catch the famed BengalTiger making its rounds through the swampy jungle.

    Visit the Mangrove(红树林)Interpretation Centre

    If you wish to spend some time indoors out of the sweatyheat, goto the Mangrove Interpretation Centre. This place is very educational withmany posters, mapsand exhibits showing the wildlife and varieties of mangrove plants found withinthe park. You'llalso get to see crocodiles in a small pool.

    Take a tour of local villages

    Experience village life that has largely remained unchangedfor centuries. Inthis vast tropical region, there are villages made up of variousethnic groups who rely on fishing, farming and working in the localthrough growing tourist industry for their livelihoods. The Sundarbans is a UNESCO worldheritage site where you can visit villages and talk to locals,who will gladly sharetheir culture with you.

    Garden of the Drunken Bai Pond

    With a history of more than 300 years, the Pond of the Drunken Bai, a classical garden in the style of Ming Dynasty, is among the Five Classical Gardens in Shanghai. "Bai" is said to be Li Bai, a famous poet in the Tang Dynasty. However, some believe that "Bai" indicates Bai Juyi, another well-known poet in the Tang Dynasty.

    Zhujiajiao Ancient Town

    Located at the bank of the Dianshan Lake in Qingpu District, Zhujiajiao Ancient Town, with a history of over 1,000 years, has been known as "Venice of Shanghai" for its simple but attractive appearance. Inside the own are rivers and bridges, giving tourists a sense of the ancient time.

    Upside-down House

    In China, the upside-down house is a new thing, but in foreign countries, it is getting more and more popular in recent years, especially in Poland. As is name suggests, the house is built inverted（倒置的）. Inside it, all the furniture and household items are placed upside down. People will feel the magic of a disorder space when walking in the house.

    Chenshan Botanical Garden

    The garden covers a total area of about 206 hectares（公顷）. Its theme is "plant and Health", combining research, education and landscape appreciation. It opened to the public in April, 2010, and is expected to be the largest one in Shanghai.

Tickets: 40 yuan per person; children under l.2m: free of charge if accompanied by an adult.

    Tablets are really useful devices, but their big screens always make them as a burden to carry around without a bag. Wouldn't it be great if there were a phone with the powers of a tablet that could be folded up and fit neatly into the hand?

    Now something like a tablet-shaped but foldable phone is about to become available. In February, South Korean electronics company Samsung and China's Huawei both launched foldable phones, the Galaxy Fold and Huawei Mate X respectively. Mobile phone use has entered the "foldable future", The Verge noted.

    The technology could change our lives in significant ways. These devices, due to their bendable screens, give us the larger screens we want. Meanwhile, they still fit easily into the pocket. As USA Today noted, they're "the combination of a small tablet and smartphone, all in a single device".

    The technology could change other devices, too. For example, we could make TVs that stick to walls like posters, or fold up easily to hide away in drawers. In crowded modem cities, they will help us to maximize available space.

    In a keynote address, Samsung's senior vice president of mobile product marketing, Justin Denison, called the foldable screen "the foundation for the smartphone of tomorrow". "It's a blank canvas (画布) for us to do something beautiful together." he said.

    So is there nothing to stand in the way of the foldable future? According to tech news website Android Authority, the necessary displays were difficult to produce. In 2012, nine out of every 10 OLED (二极管) screens produced were imperfect. Today, that 10 percent rate has been improved to between 50 and 90 percent. However, at present these foldable devices are expensive. For example, the price of Huawei Mate X is 17,500 RMB. That's a price that few people will be able to afford.

    But if the foldable device isn't going to change the world overnight, there is no doubt that it is coming. Patrick Moorhead, an industry analyst told The Verge, "Few are debating if foldable or rollable mobile displays are the future of smartphones; the only question is when and by whom."

    Nine years ago, when the closest and largest full moon fell on March 19, 2011, many people used the term, "supermoon", which we had never heard before. In 2012, we heard this term again to describe the year's closest full moon on May 6, 2012. Supermoons also appeared in 2013, 2014, 2015, 2017 and 2019.

    What does "supermoon" mean exactly? And how special was the March 19, 2011 supermoon?

    The word "supermoon" didn't come from astronomy. Instead, it came from astrology (占星学). In 1979, astrologer Richard Nolle defined it as a new or full moon which occurs at or near its closest point to the earth in its orbit. In short, the earth, moon and sun are all in a line, with the moon at its nearest point to the earth.

And the full moon of March 19, 2011 was the largest moon of that year. This "supermoon" was at perigee (近地点) — its closest point to the earth in its orbit. It was bigger and brighter than other full moons of 2011. Astronomers call this sort of close full moon a perigee full moon.

    That doesn't sound very special, does it? In fact, the March 2011 full moon lined up much more closely with perigee than Nolle's original definition. But were you able to notice with your eyes alone that this full moon was bigger or brighter than usual? Astronomers said no. But it was fun to stand outside under this full moon and know that the moon was closer than ever.

    In 2019, there were three supermoons. The first supermoon of 2019 was the Super Blood Wolf Moon on January 21, which occurred with a total lunar eclipse (月全食) at the same time, also known as a "blood moon". The second supermoon of 2019 was on February 19, also called the Snow Moon, which was the closest full moon of the year. The third and final supermoon of 2019, known by Native Americans as the Worm Moon, occurred on March 21. It fell on the day of the vernal equinox (春分), which signals the end of winter and the beginning of spring.