When we were very small, we realized that having friends was important. Some of us even had imaginary（想象中的）friends. The need for friends continued as we grew into our teens. Friends played a big part in forming our personalities（性格）. As adults, it is still important for us to have friends.

    True friends are people who like us though we made mistakes and who listen to us and tell us the truth. Friends support our decisions and tell us when we're foolish. They laugh with us and share our sadness. They are our partners and share interests with us. They stimulate us when we are feeling down. They are people we aren't afraid of telling our secret wishes to or what is really on our minds.

    Friends are our supporters. When you can depend on friends, you feel safe and warm. Friends offer acceptance and emotional（情感的） support. At times, they also help with our everyday lives, cooking a meal, doing chores, or giving us a lift when we need one. Friends also are there to offer advice, an ear to listen, or a shoulder to cry on.

    Friends also help us reduce stress. Not only do they listen to us when we feel stressed, but they also discuss what is stressing us. Sharing interests and doing activities with friends help us forget about problems at work or at home. For a short time, we can lose ourselves in a pleasant activity and perhaps laugh and breathe more easily.

    Our brains work in complex and strange ways.There are some people who can calculate the day of the week for any given date in 40,000 years,but who cannot add two plus two.Others can perform complex classical piano pieces after hearing them once,but they cannot read or write.

    Dr.J.Langdon Down first described this condition in 1887.He called these people idiot savants.An idiot savant is a person who has significant mental impairment（损伤）,such as in autism（孤独症，自闭症）or retardation.At the same time,the person also exhibits some extraordinary skills,which are unusual for most people.The skills of the savant may vary from being exceptionally gifted in music or in mathematics,or having a photographic memory.

    One of the first descriptions of a human who could calculate quickly was written in 1789 by Dr.Benjamin Rush, an American doctor.His patient,Thomas Fuller,was brought to Virginia as a slave in 1724.It took Thomas only 90 seconds to work out that a man who has lived 70 years,17 days,and 12 hours has lived 2,210,500,800 seconds. Despite this ability,he died in 1790 without ever learning to read or write.

    Another idiot savant slave became famous as a pianist in the 1860s.Blind Tom had a vocabulary of only 100 words,but he played 5,000 musical pieces beautifully.

    In the excellent movie Rain Man,made in 1988 and available on video cassette,Dustin Hoffman plays an idiot savant who amazes his brother played by Tom Cruise,with his ability to perform complex calculations very rapidly.

    Today we more clearly recognize that the idiot savant is special because of brain impairment.Yet not all brain impairment leads to savant skills.Some studies have shown that people who have purposeful interruption of the left side of the brain can develop idiot savant skills.However few people wish to participate in such experiments.There are many excellent reasons for not undergoing unnecessary experimentation on one's brain.The term idiot savant is outdated and inappropriate.Virtually all savants have a high degree of intelligence and are thus not idiots.

    Sound travels very well through water-much better, in fact, than it does through air. So it shouldn't be surprising that many ocean animals make noise. They use sound to communicate and hunt. As biologist Brandon Southall says, “Their whole world is related to sound.”

    Dolphins whistle, organizing hunts. Lovesick whales sing so loudly they can be heard hundreds of miles away. But these days they aren't the only ones sounding off. They have more and more competition from human machines.

    Every day, thousands of huge container ships sail across the world's oceans. On top of the engine noise, the ships' propeller (螺旋桨) make a loud noise all the time. All that can make it hard for ocean animals trying to listen out for friends, or dinner. Animals swimming nearby a ship can be deafened or even killed.

    Underwater construction can also be dangerously loud. When construction machines called pile drivers were used during repairs to the San Francisco-Oakland Bay Bridge, dead fish appeared.

    Geologist (地质学家) pound on the seafloor too, trying to find oil wells and map Earth's surface. The results are useful lo science, but all that hammering probably gives ocean animal a headache.

    As people realize how important sound is to ocean animals, they are looking for ways to reduce human noise. Ships could get quieter just by slowing down. Engineers are also trying to find quieter propeller ships.

    Now some companies are using a simple invention called a bubble curtain, which makes sound waves passing through it lose energy and gel quieter. It seems to work - when bubble curtains were fixed on the San Francisco bridge project fish deaths dropped.

    We still have a lot to learn about sound in the oceans, but together we can help keep the sea a quieter place.

A handsome middle-aged man walked quietly into the cafe and sat down. Before he ordered, he couldn't help but noticed a group of younger men at the table next to him. It was obvious they were making fun of something about him and it wasn't until he remembered he was wearing a small pink ribbon (丝带) on the lapel (翻领) of his suit that he became aware of what the joke was all about.

    The man pretended not to notice it, but the whisper and laughter began to get to him. He looked one of the rude young men straight into the eye, placed his hand beneath (在…下方) the ribbon and asked, “This?”

    With that the young men all began to laugh out loud. The man he spoke to said, “Hey, sorry, man, but we were just commenting on how pretty your little pink ribbon looks against your blue jacket!”

The middle-aged man calmly invited the joker to come over to his table, and politely seated him. As uncomfortable as he was, the young guy had to, not really sure why. In a soft voice, the middle-aged man said, “I wear this ribbon to bring awareness about breast cancer. I wear it in my mother's honor.”

     “Oh, sorry. She died of breast cancer?”

“No, she didn't. She's alive and well. But her breasts nourished (抚养，滋养) me as a baby, and were a soft resting place for my head when I was scared or lonely as a little boy. I'm very grateful for my mother's breasts, and her health.”

     “Umm,” the young replied, “yeah.”

     “And I wear this ribbon to honor my wife,” the man continued.

“And she's okay, too?” the young guy asked.

“Oh, yes. She's fine. Her breasts have been a great source of loving pleasure for both of us, and with them she nurtured (养育，培育) and nourished our daughter 23 years ago. I'm grateful for my wife's breasts, and her health.”

     “Uh, huh. And I guess you wear it to honor your daughter, also?”

“No. It's too late to honor my daughter by wearing it now……”

Shaken and ashamed, the young guy said, “Oh, I'm so sorry, mister.”

“So, in my daughter's memory, too, I proudly wear this little ribbon, which allows mo the opportunity to enlighten (启发，教导) others. And here…” With this, he reached in his pocket and handed the young roan a little pink ribbon. The young guy looked at it, slowly raised his head and asked, “……?”

    It is one of the oldest magic tricks in the book—a magician locks a woman in a box, with her head and feet sticking out from either end, and saws (锯) it in half. But when she finally jumps out of the box, the woman is unharmed.

    This trick was introduced nearly a century ago. It has been around for some time, but it never goes wrong. Why is it so successful? The answer is simple: the human mind is easily fooled.

    Our brain processes the world around us based on information that sensory organs, including the eyes, pick up. For instance, when we see a cow or a horse standing behind a tree, we automatically “fill in” the part of the animal's body that is hidden from our sight. “So the brain is taking this kind of very sparse (匮乏的) information about the world and it's generating this rich world by filling in information,” Stephen Macknik, a scientist at the Barrow Neurological Institute in Arizona, US, told Science magazine.

    But since our brains are filling in the gaps, sometimes they get it wrong. They tend to be driven by our previous experiences and we expect things to go as they have in the past even if sometimes they do not.

    This tendency explains magicians' success in fooling people with well-known coin tricks. For example, when you see a magician throw a coin up and down in one hand and then fake a coin thrown to the other hand, you would naturally believe that the coin is in the other hand.

Apart from the information gaps, magicians also use the “blind spots” theory when doing their shows.

    The most well-known experiment demonstrating this theory is called the “invisible gorilla (大猩猩)”, in which volunteers watch a video of two basketball teams. They are asked to count how many times the teams wearing white shirts pass the ball. In the meantime, a person dressed as a gorilla walks onto the court. But shockingly, half of the viewers don't notice the gorilla, even when they appear to be looking directly at it.

    Magicians employ this tactic (招数), what they call “misdirection”, in almost every one of their acts. They direct our attention somewhere else using comedy and music, which can make us miss stuff during the performance.

    You may probably meet most of the powerful graduation speakers, here who are well-known people in their fields. I think the schools couldn't have picked better speakers than them, because they set good examples, deeply inspiring us in our daily life.

    1) Steve Jobs, Stanford University:

    "Remembering you're going to die, and the best way I know is to avoid the trap of thinking that you have something to lose. There is no reason not to follow your heart. Your time is limited, so don't waste it living someone else's life. Don't let the noise of others' opinions drown out your own inner voice... "

    2) Oprah Winfrey, Stanford University:

    "I consider the world, this Earth, to be like a school... And the secret I've learned to get ahead is being open to the lessons from the grandest universe of all. Don't react against a bad situation. And the solution will arise from the challenge. So don't give up easily, acting with responsibility... "

    3) Bono, University of Pennsylvania:

    "For four years you've been buying, trading, and selling everything you've got in this market-place of ideas. Your pockets are full, even if your parents' are empty, and now you've got to figure out what to spend it on... The world is more flexible than you think and it's waiting for you to hammer it into shape... "

    4) Michael Dell, University of Texas at Austin:

    "Now it's time for you to move on to what's next and obtain your desire. But you must not let anything prevent you from taking those first steps. Don't spend so much time trying to choose the perfect opportunity, or sometimes you'll miss the right opportunity. Recognize that there will be failures and obstacles. But you will learn from your mistakes and the mistakes of others."