My 16-year-old son, Anton, had gone to the local swimming hole． Most of the kids swim there, and there are plenty of rocks for them to use as safe harbors, so I had no fears for his safety．

    Still, the firefighter's first words "You need to come up here to the Stillwater River" made me catch my breath, and his follow-up words gave me relief: “Your son is OK．”

    When I got to the river, I immediately saw the firetruck, ambulance and Anton, wrapped with a towel about his shoulders, sitting quietly on a low platform of the fire engine．I hurried over to him． "You OK?"I asked．

    “Yeah,” was all he said． But my eyes begged for an explanation, I didn't get it from my son, however, who tends to play his cards close to his vest ．

    The story was this: A woman was being swept under water． Hearing the cries, Anton and his friend Tyler, without hesitation, swam out to her, and brought her safely to shore.

    In an age in which the word "hero" is broadcast with abandon and seemingly applied to anyone who makes it through the day, I realized the real thing in my son. The teens are stubborn and self-centered, but that didn't mean they have no desire to do good.

    Still shocked by my son's daring, I drove him home. Along the way, I tried to dig out some more information from him but he had precious little to say. The only words he said were, “What's for supper?”

    I spent some time alone that evening, thinking about the tragedy that might have been. The next morning, when Anton got up, I half expected him to tell me the story. But all he did was toast some bread, pull himself together, and head for the door to start a new day. Watching from the window, I was reminded that still water often runs deep.

    Probably no other musical instrument is as popular as the guitar around the world. Musicians use the guitar for almost all kinds of music. Country and western music would not be the same without a guitar. The traditional Spanish folk music called Flamenco could not exist without a guitar. The sound of American blues music would not be the same without the sad cry of the guitar. And rock and roll music would almost be impossible without this instrument.

    Music experts do not agree about where the guitar was first played. Most agree it is ancient. Some experts say an instrument very much like a guitar was played in Egypt more than 1,000 years ago. Most experts say that the ancestor of the modern guitar was brought to Spain from Persia sometime in the 12^th century. The guitar continued to develop in Spain. In the 1700s it became similar to the instrument we know today.

    Many famous musicians played the instrument. The famous Italian violins Niccole Paganism played and wrote music for the guitar in the early 1800s. Franz Schubert used the guitar to write some of his famous works. In modern times Spanish guitarist Andres Segovia helped make the instrument extremely popular.

    In the 1930s, Les Paul began experimenting to make an electric guitar. He invented the solid-bodied electric guitar in 1946. The Gibson Guitar Company began producing its famous Les Paul Guitar in 1952. It became a powerful influence on popular music. The instrument has the same shape and the same six strings (弦) as the traditional guitar, but it sounds very different. Les Paul produced a series of extremely popular recordings that introduced the public to this music. Listen to this Les Paul recording. It was the fifth most popular song in the United States in 1952. It is called “Meet Mister Callaghan.”

    It encouraged us to visit Quora. com, the online question and answer community, to find out how users get the most out of every tank of gas.

    Light makes right

    Alex Elderfield noted that excess weight prevents an engine from burning fuel efficiently. "Only carry what is essential in your car, clean out any junk or necessary items otherwise you are paying for the fuel to cart these from place to place," he wrote.

    Driving smoothly — that is, not mashing the gas and then slamming the brakes later down the road — was a fixture of many responses. Quora user Clint Law agreed on that advice, who wrote, "Every little bit of kinetic energy that your brakes lose, your engine burned in fuel to build up." Overbraking should consequently be viewed as wasted acceleration. "That's really what kills your fuel economy," he argued.

    Keep the pressure up

    Keeping the recommended tire pressure for your car was another mantra among Quora users. Marlyn Rosent said she checked her tire pressure every time she filled up her SUV. Quora user Doug Dingus checks his tire pressure every weekend. “Less tire contact means reduced rubbing, requiring less fuel,” he said.

    Air conditioning or windows

    Though the summer heat get many drivers to roll up the windows and turn on the air conditioning, some people argued that running the A/C wastes too much gas. In between were many shades of grey.

    Achilleas Vortselas said it would depend largely on a car's speed. He wrote that as a general rule, people should drive with the windows down around the city and turn the air conditioning on when hitting the highway, where a car's aerodynamic(空气动力的) characteristics would be influenced by opened windows.

    More seriously minded people, however, said to travel as much as possible with windows up and the A/C off. Eddie Xue gets by with just a wisp of outside air. “Use the fan and open your windows every now and then at lower speeds," he wrote.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

    You may not know a lot of people when you start high school. Maybe your friends from middle school are going to a different high school. Even if you know other freshmen(新生), you still feel nervous that you don't know any upper-classmen. How are you going to make friends among this sea of unknown faces?

    Most high schools hold a freshman orientation(训练) before school actually starts. These are helpful not only because you learn your way around the building and get to meet some of your teachers, but you also get to meet fellow freshmen. That way, when you show up on your first day of school, you may already recognize a few familiar faces.

    When you talk to people at orientation, you'll probably find that a lot of them are feeling just like you are. They're all new to the school and don't know what to expect. Talking about a common concern with your classmates can help you develop friendships.

    The work in high school is something freshmen are probably worried about. The work in high school builds on what you learned in middle school, giving you a more advanced knowledge of many subjects. So you may find you have more work to do or that it's a bit more challenging. If you ever find your work too difficult, teachers can give you extra help.

    High school also has more after-school activities than middle school did, such as clubs, music and theater groups and sports teams. This is a good time to explore your interests and try new things.

    Middle school taught you the basics of academics, time management, and social skills while providing you with a little extra support and guidance. High school gives you the chance to learn how to be more independent and responsible.

    We may think we're a culture that gets rid of our worn technology at the first sight of something shiny and new, but a new study shows that we keep using our old devices (装置)well after they go out of style. That's bad news for the environment—and our wallets—as these outdated devices consume much more energy than the newer ones that do the same things.

    To figure out how much power these devices are using, Callie Babbitt and her colleagues at the Rochester Institute of Technology in New York tracked the environmental costs for each product throughout its life—from when its minerals are mined to when we stop using the device. This method provided a readout for how home energy use has evolved since the early 1990s.Devices were grouped by generation. Desktop computers, basic mobile phones, and box-set TVs defined 1992.Digital cameras arrived on the scene in 1997.And MP3 players, smart phones, and LCD TVs entered homes in 2002, before tablets and e-readers showed up in 2007.

    As we accumulated more devices, however, we didn't throw out our old ones.“The living-room television is replaced and gets planted in the kids' room, and suddenly one day, you have a TV in every room of the house,” said one researcher. The average number of electronic devices rose from four per household in 1992 to 13 in 2007.We're not just keeping these old devices—we continue to use them. According to the analysis of Babbitt's team, old desktop monitors and box TVs with cathode ray tubes are the worst devices with their energy consumption and contribution to greenhouse gas emissions (排放)more than doubling during the 1992 to 2007 window.

    So what's the solution (解决方案)?The team's data only went up to 2007,but the researchers also explored what would happen if consumers replaced old products with new electronics that serve more than one function, such as a tablet for word processing and TV viewing. They found that more on-demand entertainment viewing on tablets instead of TVs and desktop computers could cut energy consumption by 44%.

A few years ago, I returned from a family vacation in Mexico, where I'd bought myself a beautiful blue candle. I was so excited to light it. But when I got home and unpacked it, I thought, "Today is not the day. I'm going to save it for the right occasion." So I put it in my closet and forgot about it.

Two years passed, I remembered my candle and I thought, "Today is the day. I'm going to light it." So I went to the closet and opened up the box—and my beautiful blue candle had turned into wax. Now what struck me is my candle did exactly what it's designed to do—melt—but it did it without me.

That candle which melted triggered (触发) something in me. It old the story to my friend Gillian. The next time I was over at her house, she took me on a tour and she showed me that all of her candles had been lit. She told me, "I had waited a year to light those candles. You told me the story, and I lit them all the next day. "

I believe, however, that those small actions send a big message and show you're no longer letting life slip— or melt—by.

Here's my advice for you: Whatever object you answered "yes" to earlier, please use it with in the next week. Pull out your china for a random Tuesday night, open the Scotch, and cut the tags off a jacket. And don't let your candle melt in the closet.