You know that balloons must be kept away from sharp objects. They also needed to be kept away from flames. A fire can weaken the rubber and cause it to break. However, in this experiment you will find out how you can hold a balloon directly in a flame without breaking the balloon.

    Materials needed:

● two round balloons not inflated(充气的)

● several matches

● water

    Inflate one of the balloons and tie it. Place 1/4 cup of water in the other balloon, and then inflate it and tie it. Light a match and hold it under the first balloon. Allow the flame to touch the balloon. What happens? The balloon breaks, perhaps even before the flame touches it. Light another match. Hold it directly under the water in the second balloon. Allow the flame to touch the balloon. What happens to this balloon? It doesn't break.

    Why does the balloon with no water break in the flame? The flame heats the rubber of both balloons. The rubber of the balloon without water becomes so hot that it becomes too weak to resist the pressure of the air inside the balloon. However, when the balloon with water in it is placed in the flame, the water takes in most of the heat from the flame. Then, the rubber of the balloon doesn't become very hot, it doesn't weaken, and the balloon doesn't break.

    Water is a particularly good absorber(吸收者) of heat. It takes a lot of heat to change the temperature of water. On the other hand, when water cools, it gives off a great deal of heat. That's why areas near oceans or other large bodies of water don't get as cold in winter as areas at the same latitude(纬度) further inland.

    Put your car keys away and forget about your travel pass — it's time to do a bit of walking.

    National Walking Month is organized every May by Living Streets, an organization that campaigns for the rights and the needs of pedestrians — indeed, the organization was previously known as the Pedestrians' Association. The association's aim is to make streets safe, attractive and enjoyable spaces for people to live, work, shop and play. By putting people (rather than vehicles) first, Living Streets wants to create streets and spaces where people feel happier, healthier and more sociable.

    The annual campaign gives participants a great opportunity to experience the many virtues（优点）of walking. These include the physical health benefits of becoming fitter; the environmental advantages of not using vehicles（车辆）; the joy of local discoveries seeing more of your local area on foot; the enjoyment of walking with other people, whether family, friends or work colleagues and finally the stress relief that comes from walking—walking can clear your head.

    Walk to School Week, 19 to 24 May, is part of the month's activities and its aim is to encourage parents to send children to school on foot, rather than take them in the car or let them use public transport. The movement was started in 1995 with only five participating schools and now two decades later, more than one million children take part.

    Similarly, there is Walk to Work Week, 12 to 16 May, where grown-ups are encouraged to walk. In the morning, getting off the bus a stop early or parking a few streets away is a good way to add more steps to the daily total. And during the working day, rather than having lunch at the desks or in the canteen, take a walk and get some fresh air. Walk home with your workmates and chat away about everything under the sun but work!

    Do you love Beats headphones, True Religion jeans, and UGG shoes? These are some of the most popular brands (牌子) around. They are also expensive. But some experts say they are not much better than cheaper brands.

    For example, Jim Wilcox works for Consumer Reports. He tested all kinds of headphones. He says that $80 Koss Pro headphones provide basically the same quality (质量) and comfort as Beats. So why do people pay twice or even 10 times as much for the hottest brands?

    Experts say it's because fashionable, expensive brands send a message. Brands say “I belong” or “I can afford it.”

    Some people think that expensive brand names are worth the price. They say that some designer clothes really are top quality and that they last longer than cheaper brands. Some teenagers choose to wear popular brands because these brands make them feel good about themselves.

    Alexandra Allam, 17, likes to buy brand-name products. “I'd rather spend the extra money to get something I know I'll be satisfied with,” she says. Her friend Emmy Swan agrees, saying “As long as you can afford it, it seems reasonable to buy what you want.” But not all teenagers agree. “Spending hundreds of dollars for designer sunglasses is stupid and unreasonable,” says Daniel Steinbrecher, 16. “It's fake (假的) happiness.”

    People who are against wearing expensive brand names say that many designer brands aren't any better. “It's wasteful to buy things just because they are popular,” says Edmund Williams, 15. “You'll feel better if you buy things because you like them. If you have extra money to spend, it would be better to give it to people in need.”

    Reports tell us that Americans work more and vacation less than people in other major industrial countries. Still, millions of Americans do try to get away from home for a week or two in the summer months. Some might even have the time and money to spend longer on vacation.

    For example, many retired Americans can be found driving around the United States in big recreational vehicles, known as R. V.'s. These serve as a home away from home. In fact, it might even be their only home as they see the country.

    Some American families get in their cars and drive to historic places like Colonial Williamsburg in Virginia. There, they can experience what life was like for early Americans. If that is not exciting enough, also in Williamsburg is a water park and an amusement park with rides.

    Other Americans visit national parks like Yellowstone or Yosemite out in the West. They want to spend time with nature. Or they take their vacation by a lake or the ocean. They might swim or fish. But many just want to sit and enjoy the feeling of doing nothing, except maybe read a book.

    Some families fly to other countries on vacation. Or they go on a cruise ship (大型游轮) and stop in different ports. Cruise ships are like floating cities.

    But not everyone goes someplace special on vacation. This might be the only time for people to work on things like home improvement projects. And while they do that, they might think of all the fun their friends are having.

The Handshake

    I don't remember the exact date I met Marty for the first time. Like a lot of people who want to get through a checkout line, I found my thoughts on speed, nothing more. The line I was standing in wasn't moving as quickly as I wanted, and I glanced toward the cashier, who was receiving money from customers.

    He was an old man in his sixties. I thought, well, it probably took him a little longer to get the jobs done. For the next few minutes I watched him. He greeted every customer before he began scanning the goods they were purchasing. Sure, his words were the usual, “How's it going?” But he did something different—he actually listened to people. Then he would respond to what they had said and talk with them briefly.

    I thought it was strange, but I guessed I had grown accustomed to people asking me how I was doing simply out of a conversation without thinking. Usually, after a while, you don't give any thought to the question and just say something back quietly.

    This old cashier seemed sincere about wanting to know how people were feeling. Meanwhile, the high-tech cash register rang up their purchases and he announced what they owed. When customers handed money to him, he pushed the appropriate keys, the cash drawer popped open, and he counted out their change.

    Then magic happened.

    He placed the change in his left hand, walked around the counter to the customers, and extended his right hand in an act of friendship. As their hands met, the old cashier looked the customers in the eyes. “I want to thank you for shopping here today,” he told them. “You have a great day. Bye-bye.” The looks on the faces of the customers were priceless.

    Now it was my turn. I glanced down at the name tag on his red waistcoat, the kind experienced Wal-Mart cashier wore. It read, “Marty.”

    Marty told me how much I owed and I handed him some money. The next thing I knew he was standing beside me, offering his right hand and holding my change in his left hand. His kind eyes locked onto mine. Smiling, and with a firm handshake…

    It was May 23, 2016. Arnot, the 32-year-old mountain guide, reached the top of Everest without the use of oxygen (O2) equipment. It was achieved after seven years, three previous attempts, and fourteen straight hours of climbing.

After 15 minutes at the top, Arnot began her descent (下坡). Eight hours later, she reached the camp at 7, 600 meters and became the first American woman-and only the seventh woman ever—to successfully reach Mount Everest without oxygen equipment.

    "There are so many reasons for her impressive achievement, especially the physical and emotional efforts that she has put forth over the years to make this happen," says the professional climber and photographer Richards, "The mental courage that it requires is something very few people have."

    Arnot didn't start climbing until she was 19 years old. Money was tight in her family, and climbing mountains never occurred in her mind. After graduating from college, Arnot was invited by her friend to climb a mountain. "It totally changed my life," says Arnot. I always know that if you want something, you can achieve it, but knowing what you want is a whole different thing," she says. "I am athletic but not competitive. After my first climbing, I knew immediately that mountains are what I want—as that is where I felt home for the first time in my life."

    After that first climb, she devoted herself to learning how to climb and move through mountain. It was during her second trip to Everest in 2009 that she first set her sights on a no-oxygen attempt. However, while hiking into Everest Base Camp that year, she hurt her leg and wasn't able to climb without oxygen. In 2013 she nearly made it to the top, but was forced to take oxygen at 8,504 meters while helping another climber.

    When Arnot finally stood at the top Everest, she called her best friend, "I reached the top and I'm not using any oxygen." Then, tears began to stream down from her eyes. So much of Arnot's life has been about pushing the limits of her abilities, and in this case, she's also pushed up against the outer limits of the human spirit.