Outside, it's a cold winter's day. Inside a large shopping center, people are hanging around. But then, without warning, a pop song starts to play loudly. A teenager boy walks lazily to the center of the open space, and dances crazily to the music. He's joined by two of his friends, then some of the old people. In a few seconds，more than sixty people are dancing to the music—all in time and all in step. At first, onlookers(旁观者)are puzzeled, and then they start smiling and clapping. They now know what they're seeing: a flash mob(快闪).

    According to Wikipedia, the term "flash mob" was created by Bill Wasik, an editor at Harper's Magazine, in 2003. In a year, the phrase had entered the Concise Oxford English Dictionary. Since then, hundreds—possibly thousands—of flash mobs have been performed around the world, in almost every kind of public space imaginable!

    Each flash mob has its own style，but most flash mobs follow a similar formula(方案). Often, the organizers search for willing participants(参与者)using social media. Instructions and dance moves are given through the Internet. There are usually several rehearsals(排练)before the big day.

    While it's happening, a few lucky passers-by watch it live. Most people who watch it, however, will see it later online. Some of the most popular flash mobs on YouTube have been watched more than 10 million times. A famous example is MP3 Experiment Eight, a flash mob that took place in New York City in July 2011 with over 3,500 participants. This event was different from normal flash mobs in that much of it was completely silent—and there were no rehearsals.

    Flash mobs provide the participants, onlookers and online viewers with a lot of enjoyment and pleasure. For this reason alone, they're a modern, popular art form that should be celebrated.

    It's hard to make friends if you stay at home all the time, so get out of the house and do things that will put you in touch with(接触)other people. It's easier to make friends with them when you find you like the same things as other people.

Don't be afraid to show people what you're really good at. You can talk about the things you like and do best. People will be interested in you if they, hear something interesting about you.

    Look at people in your eyes when you talk to them. That way, they'll find it easier to talk to you, or people may think you're not interested in them and may stop being interested in you.

    Be a good listener. Let people talk about themselves before talking about "me, me, me” You can ask people lots of questions and show that you are interested in their answers.

    Try to make friends with the kind of people you really like, respect(尊敬)and admire(羡慕). You shouldn't just make friends with those people you will meet them easily. Try to be friendly with all kinds of people. That way, you'll have a bigger group of people to choose from. Then you'll be easier to make friends with other people.

① Do you have a dog? What can your dog do for you? Do you know that dogs can read our feelings? Now some people find that dogs can smell (v.闻到; n.嗅觉) people's stress (压力).

②Dogs really are man's best friends. They have special smell. A new study said that dogs can smell if people are feeling stressed. Teachers at Queen's University, UK, made the study. They got breath(呼吸)and sweat(汗) from people both before and after doing a hard maths problem. They looked at the people's heart rate (心率), blood pressure (血压) and stress feeling in the study. Dogs can smell the difference in breath and sweat from people. Then they can know when people are stressed.

③The finding is wonderful: the dogs found stress in 675 of the 720 people. It could be 93.75% right! Australian News reported. The study's writer Clara Wilson said, "stress can change people's breath and sweat. Dogs are very good at smelling these changes." In the study, she also said, "this finding helps us learn that how dogs may know people's feelings."

④ This finding shows how special the bond is between people and dogs. The finding also tells us that dogs are very clever. And maybe dogs can help stressed people.