A popular saying goes, "Sticks and stones may break my bones, but words will never hurt me." However, that's not really true. Words have the power to build us up or knock us down. It doesn't matter if the words come from someone else' or ourselves—the positive and negative effects are just as lasting.

    We all talk to ourselves sometimes. We're usually too shy to admit it, though. In fact, more and more experts believe talking to ourselves out loud is a healthy habit.

    This "self-talk" helps us encourage ourselves, remember things, solve problems, and calm ourselves down. Be aware, though, that as much as 77% of self-talk tends to be negative. So in order to stay positive, we should only speak words of encouragement to ourselves. We should also be quick to give ourselves a pat on the back. The next time you finish a project, do well in a test, or finally clean your room, join me in saying "Good job!"!

    Often, words come out of our mouths without thinking about the effect they will have. But we should be aware that our words cause certain responses in others. For example, when returning an item to a store, we might use warm, friendly language during the exchange. And the clerk will probably respond in a similar manner Or harsh (刻薄的)and critical language will most likely cause the clerk to be defensive.

    Words have power because of their lasting effect. Many of us regret something we once said. And we remember unkind words said to us! Before speaking, we should always ask ourselves: Is it loving? Is it needed? If what we want to say doesn't pass this test, then it's better left unsaid.

    Words have power: both positive and negative. Those around us receive encouragement when we speak positively. We can offer hope, build self-esteem(自尊) and encourage others to do their best Negative words destroy all those things. Will we use our words to hurt or to heal? The choice is ours.

    Social media is one of the fastest growing industries in today's world. A study conducted by the US Pew Research Center showed that 92 percent of teenagers go online daily. The wide spread of social media has changed nearly all parts of teenagers' lives.

    Changing relationships

    High school student Elly Cooper from Illinois said social media often reduces face- to-face communication. “It makes in-person relationships harder because of people's attention given to their phones instead of their boyfriends or girlfriends,” Cooper said.

    Yet, some people believe social media has made it easier to start relationships with anyone from anywhere. Beth Kaplan from Illinois met her long-distance friend through social media. He currently lives in Scotland, but they're still able to frequently communicate with each other. “I can feel close to someone that I'm talking to via FaceTime,” Kaplan said.

    Wanting to be “liked”

    The rise of social media has changed the way teenagers see themselves. The 19- year-old Essena O'Neill announced on the social networking service Instagram that she was quitting social media because it made her unable to stop thinking about appearing perfect online. Negative comments also can do great damage to a teenager's self-esteem. Teenagers who get negative comments can't help but feel hurt.

    Opening new doors

    However, Armin Korsos, a student from Illinois, takes advantage of the comments he receives over social media to improve his videos on the social networking site YouTube. “Social media can help people show themselves and their talents to the world in a way that has never been possible before,” Korsos said.

    If you go into the forest with friends, stay with them. If you don't, you may get lost. If you get lost, this is what you should do. Sit down and stay where you are. Don't try to find your friends—let them find you. You can help them find you by staying in one place. There is another way to help your friends or other people to find you. You can shout or whistle(吹口哨) three times. Stop. Then shout or whistle three times again. Any signal given three times is a call for help.

    Keep up shouting or whistling. Always three times together. When people hear you, they will know that you are not just making a noise for fun. They will let you know that they have heard your signal. They will give you two shouts or two whistles. When a signal is given twice, it is an answer to a call for help.

    If you don't think that you will get help before night comes, try to make a little house with branches(树枝). Make yourself a bed with leaves and grass.

    When you need some water, you have to leave your little branch house to look for it. Don't just walk away. Pick off small branches and drop them as you walk in order to go back again easily. When you are lost, the most important thing to do is to stay in one place.

    These days, I walk down the steps leading toward the south end of the All England Club in Wimbledon, and still look for the Crow's Nest, a small green observation tower with an outer ladder that I used to climb on for a wide view of the grounds, but which has since been knocked down.

    The Crow's Nest was a particularly useful point, because it allowed a tennis writer to keep track of the action on as many as 10 outside courts at a time. At days end, reporters from different nations would share notes on what they had observed all over the grounds.

    Twenty-seven years later, the press room has touch screens that allow us to watch live videos from any court, and even go back to watch key moments in key matches long after they have finished. You could cover Wimbledon without leaving your seat. But that is a bit like spending all your time ordering room service and looking up fun facts on Wikipedia.

    More than at any other tennis tournament, there is also an appetite for stories that deal with the setting, the history and the traditions.

    If they change the price of the fish tacos (鱼肉卷饼) at the United States Open, it's not a story. If they change the price of the strawberries and cream, the signature treat at Wimbledon. It's time to email your editor using capital letters.

    The new retractable (可伸缩的) roof was put in place in 2009. Until then, you always had to have a rainy-day story in your notebook because there were no guarantees any matches would be played. Now tennis is a sure thing on Centre Court, which has made tennis reporters a bit less creative. But at least it guarantees us daily access to the most atmospheric place in the sport.

    So much has changed, but Centre Court remains true to its original spirit: more a theater than a stadium. Catching that feeling is part of covering Wimbledon, too.

    Humans and many other mammals have unusually efficient internal temperature regulating systems that automatically maintain stable core body temperatures（核心体温）in cold winters and warm summers. In addition, people have developed cultural patterns and technologies that help them adjust to extremes of temperature and humidity（湿度）.

In very cold climates, there is a constant danger of developing hypothermia（低体温）, which is a life threatening drop in core body temperature to below normal levels. The normal temperature for humans is about 37.0℃. However, differences in persons and even the time of day can cause it to be as much as 6℃ higher or lower in healthy individuals. It is also normal for core body temperature to be lower in elderly people. Hypothermia begins to occur when the core body temperature drops to 34.4℃. Below 29.4℃, the body cools more rapidly because its natural temperature regulating system usually fails. The rapid decline in core body temperature is likely to result in death. However, there have been rare cases in which people have been saved after their temperatures had dropped to 13.9-15.6℃. This happened in 1999 to a Swedish woman who was trapped under an ice sheet in freezing water for 80 minutes. She was found unconscious, not breathing, and her heart had stopped beating, yet she was eventually saved despite the fact that her temperature had dropped to 13.7℃.

In extremely hot climates or as a result of uncontrollable infections, core body temperatures can rise to equally dangerous levels. This is hyperthermia. Life threatening hyperthermia typically starts in humans when their temperatures rise to 40.6-41.7℃. Only a few days at this extraordinarily high temperature level is likely to result in the worsening of internal organs and death.

    "Bill, you never miss!" Joe said admiringly. "Unless I'm in a real game," Bill complained. "Then I miss all the time." Joe knew that Bill was right. Bill performed much better when he was having fun with Joe in the school yard than he did when he was playing for the school team in front of a large crowd. "Maybe you just need to practice more," Joe suggested. "But I practice all the time with you!" Bill objected. He shook his head. "I just can't play well when people are watching me." "You play well when I'm watching," Joe pointed out. "That's because I've known you since we were five years old," Bill said with a smile. "I'm just not comfortable playing when other people are around." Joe nodded and understood, but he also had an idea.

    The next day Joe and Bill met in the school yard again to practice. After a few minutes, Joe excused himself. "Practice without me," Joe said to his friend. "I'll be back in a minute. "

    Joe hurried through the school building, gathering together whomever he could find-two students, a math teacher, two secretaries, and a janitor(看门人). When Joe explained why he needed them, everyone was happy to help. Joe reminded the group to stay quiet as they all went toward the school's basketball court. As Joe had hoped, Bill was still practicing basketball. He made five baskets in a row without noticing the silent people standing behind him.

    "Hey, Bill!" Joe called out finally. Bill turned. A look of surprise came over his face. "I just wanted to show you that you could play well with people watching you," Joe said. "Now you'll have nothing to worry about for the next game!"