If you see a group of people dancing and singing on the street or in the railway station,  you don't need to feel surprised．They are a flash mob （快闪族）, which is a group of people who come together suddenly in a public place, do something unusual for a brief period of time,  and then quickly break up．They are usually organized with the help of the Internet or other digital communication network．At a predetermined time, they gather and perform some  distractions（消遣） such as waving their hands and exchanging books, Then, they quickly break up before the police can arrive．Using mobile phones, the flash mob can change its location if the first one has been replaced for any reason．

    Bill Lasik, senior editor of Harper's Magazine, organized the first flash mob in Manhattan in May 2003 and the first successful flash mob came together on June 3, 2003 - after the first try was foiled at Macy's department store．Lasik claimed that the activity was designed to make fun of hipsters （起时髦的人）, and call attention to the cultural atmosphere．

    Flash mob gatherings can sometimes shock people．Such an activity might seem amusing and untrue, but it also might frighten people who are not aware of what is taking place．Undoubtedly, flash mobs can serve as good political tools in any direction．They also have great economic potential, such as using flash mobs to advertise a product．

    The flash mob is now becoming more and more popular．People use it to do many things．For example, in 2009, Michael Jackson's fans took part in a flash mob to remember him．Hundreds of his fans gathered singing and dancing Michael's famous song "Beat It" together．Flash mobs give people from all walks of life an opportunity to come together to create a memory．

    In colleges around the country, most students are also workers. The reality of college can be pretty different from the images presented in movies and television. Instead of the students who wake up late, party all the time, and study only before exams, many colleges are full of students with pressing schedules of not just classes and activities, but real jobs, too.

    This isn't a temporary phenomenon. The share of working students has been on the rise since the 1970s, and one-fifth of students work year round. About one-quarter of those who work while attending school have both a full-course load and a full-time job. The arrangement can help pay for tuition (学费) and living costs, obviously. And there's value in it beyond the direct cause: such jobs can also be critical for developing important professional and social skills that make it easier to land a job after graduation. With many employers looking for students with already-developed skill sets, on-the-job training while in college can be the best way to ensure a job later on.

    But it's not all upside. Even full-time work may not completely cover the cost of tuition and living expenses. The study notes that if a student worked a full-time job at the federal minimum wage, they would earn just over $15,000 each year, certainly not enough to pay for tuition, room, and board at many colleges without some serious financial aid. That means that though they're sacrificing time away from the classroom, many working students will still graduate with at least some debt. And working full time can reduce the chance that students will graduate at all, by cutting into the time available for studying and attending classes.

    There is little reward for attending but not finishing college. Students who end up leaving school because of difficulty in managing work and class are likely to find themselves stuck in some of the same jobs they might have gotten if they hadn't gone at all. The difficulty of working too much while in school can create a cycle that pushes students further into debt without receiving any of the financial or career benefits.

    Washington, D.C. Bicycle Tours

    Cherry Blossom Bike Tour in Washington, D.C.

    Duration: 3 hours

    This small group bike tour is a fantastic way to see a world-famous cherry trees with beautiful flowers of Washington, D.C. Your guide will provide a history lesson about the trees and the famous monuments where they blossom. Reserve your spot before availability — the cherry blossoms—disappear!

    Washington Capital Monuments Bicycle Tour

    Duration: 3 hours (4 miles)

    Join a guided bike tour and view some of the most popular monuments in Washington, D.C. Explore the monuments and memorials on the National Mall as your guide shares unique facts and history at each stop. Guided tour includes bike, helmet, cookies and bottled water.

    Capital City Bike Tour In Washington, D.C.

    Duration: 3 hours

    Morning or Afternoon, this bike tour is the perfect tour for D. C. newcomers and locals looking to experience Washington, D.C. in a healthy way with minimum effort. Knowledgeable guides will entertain you with the most, interesting stories about Presidents, Congress, memorials, and parks. Comfortable bikes and a smooth tour route(路线) make cycling between the sites fun and relaxing.

Washington Capital Sites at Night Bicycle Tour

    Duration: 3 hours (7miles)

    Join a small group bike tour for an evening of exploration in the heart of Washington, D.C. Get up close to the monuments and memorials as you bike the sites of Capitol Hill and the National Mall. Frequent stops are made for photo taking as your guide offers unique facts and history. Tour includes bike, helmet, and bottled water. All riders are equipped with reflective vests and safety lights.

    Suppose you work in a big firm and find English very important for your job because you often deal with foreign businessmen. Now you are looking for a place where you can improve your English, especially your spoken English.

    Here are some advertisements about English language training from newspapers.

    You may find the information you need.

    Global English Center

    General English in all four skills：listening, speaking, reading, and writing.

    3-month(700yuan), 6-month(1200yuan)and one-year(2000yuan)courses.

    Choice of morning or evening classes, 3 hours per day. Mon-Fri.

    Experienced college English teachers.

    Close to city center and bus stops.

    Tel：67605272 Add：105 Zhongshan Road, 100082.

    Modern Language School

    Special courses in English for business, traveling, banking, hotel management and office skills.

    Small classes(12-16 students)on Sat. ＆Sun. From 2∶00-5∶00pm.

    Native English teachers from Canada and USA.

    Language lab and computers supplied.

    3-month course：1,050yuan; 6-month course：1,850yuan.

    Write or phone：Modern Language School, 675Park Road. 100056

    Tel：67353019

    The 21st Century English raining Center

    We specialize in effective teaching at all levels.

    We offer morning or afternoon classes, both of which last three months and a half at a cost of 800yuan.

    We also have a six-week TOEFL preparation class during winter and summer holidays.

    Entrance exams：June 1 and Dec. 1.

    Only 15-minute walk from city center.

    Call 67801642 for more information.

    The International House of English

    Three/Six-month English courses for students of all levels at very low cost：60yuan for 13 hours per week; convenient class hours：9∶00－12∶00am and 2∶00－5∶00pm.

    A four-month evening program for developing speaking skills(same cost as day classes).

    Well-trained Chinese and foreign teachers experienced in teaching English as a second/foreign language. Free sightseeing and social activities. Very close to Central Park.

    For further information call 67432308.

    People have different ways of dealing with a common cold. Some take over-the- counter(非处方的) medicines such as aspirin while others try popular home remedies(治疗)like herbal tea or chicken soup. Yet here is the tough truth about the common cold: nothing really cures it.

    So why do people sometimes believe that their remedies work? According to James Taylor, professor at the University of Washington, colds usually go away on their own in about a week, improving a little each day after symptoms peak, so it's easy to believe it's medicine rather than time that deserves the credit, USA Today reported.

    It still seems hard to believe that we can deal with more serious diseases yet are powerless against something so common as a cold. Recently, scientists came closer to figuring out why. To understand it, you first need to know how antiviral(抗病毒的) drugs work. They attack the virus by attaching to and changing the surface structures of the virus. To do that, the drug must fit and lock into the virus like the right piece of a jigsaw(拼图), which means scientists have to identify the virus and build a 3-D model to study its surface before they can design an antiviral drug that is effective enough.

    The two cold viruses that scientists had long known about were rhinovirus(鼻病毒) A and B. But they didn't find out about the existence of a third virus, rhinovirus C, until 2006. All three of them contribute to the common cold, but drugs that work well against rhinovirus A and B have little effect when used against C.

    "This explains most of the previous failures of drug trials against rhinovirus," study leader Professor Ann Palmenberg at University of Wisconsin-Madison, US, told Science Daily.

    Now, more than 10 years after the discovery of rhinovirus C, scientists have finally built a highly-detailed 3-D model of the virus, showing that the surface of the virus is, as expected, different from that of other cold viruses.

    With the model in hand, hopefully a real cure for a common cold is on its way. Soon, we may no longer have to waste our money on medicines that don't really work.