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.

At night, you fall asleep while listening to beautiful music. In the morning, the singing of birds outside wakes you up. You can enjoy all of these things because of one important organ(器官)— the ear.

You may wonder: how do our ears work? The ear has three different parts: the outer ear, the middle ear and the inner ear. The outer ear is the part you can see. It collects sound around you. The sound then travels down to the middle ear, the inner ear and then to your brain.

Your ears never stop working, even when you are asleep! Your ears continue hearing sounds, but your brain just ignores (忽略) them. That's why you may sometimes wake up suddenly in the middle of the night—your brain hears something, but you don't know what it is, since you are asleep.

But ears do more than hear. They help you keep your balance, too. In the inner ear, there are organs that are filled with liquid (液体) and covered in small hairs. When you move your head, the liquid and hairs move, too. They send messages to your brain about the position of your head.

More surprisingly, ears even help with tasting food. Of course, you don't actually taste food with your ears. But there are nerves (神经) running through the middle ear that connect the tongue (舌头) to the brain.

The ears are truly important. Everyone should make sure to protect their ears as well as they can.

Do you know that there are many things to do to keep our bodies healthy? One answer may be looking after our lungs(照顾好我们的肺). Our lungs help us breathe(呼吸), and breathing keeps us alive! So it is important to look after our lungs.

 One way to look after our lungs is by doing physical exercise often. When we play sports, our lungs must work harder. Our lungs breathe in clean fresh air. The air is used by the heart. The heart then pushes blood around different parts of our body to make them healthier.

 Another important thing is to choose to do healthy things. This means eating lots of colourful fruits and vegetables, drinking lots of water and getting enough sleep.

 But sometimes, we might meet things that aren't so good for our lungs, like smoking. When some people try to ask us to smoke, it's important to say no.

 Do you know that May 31 every year is World No Tobacco Day(世界禁烟日)? The subject this year is" Keeping Children away from Tobaccos". Countries around the world should let children know they should not smoke through the Internet.

 When we choose not to smoke, we' re not only helping our lungs. We' re also helping our body health.

Italki is a website where you can ask questions about any language you want and get answers from native speakers and other language learners from around the world. You can also teach others about your own native language. The following posts are about English learning.

Taking Care of Your Eyes

Eyes are important to you, and good eyes help you see the world clearly. But it's very common to see many people wearing glasses these days. You must want to know how to take good care of your eyes. Here are some questions for you to think over.

{#blank#}1{#/blank#} When you stare at computers or phones for a long time, your eyes often feel tired. So, try to spend less time on screens and enjoy more time with your friends and family.

Do you give your eyes lots of rest? When you are watching TV or playing online games, remember to take breaks. After 20 minutes of work on the screen, look at something 20 feet away for at least 20 seconds. It's really useful. {#blank#}2{#/blank#} When you have enough sleep, your eyes can get ready for the work of the new day.

How many hours should you spend on outdoor activities? {#blank#}3{#/blank#} The natural light and the real beauty help your eyes stay healthy.

Do you like to eat fruit and vegetables? {#blank#}4{#/blank#}  Your eyes need them. They help your eyes get the things they need to work at their best.
 

How do you protect your eyes? (no more than 10 words){#blank#}5{#/blank#}