Researchers at Brigham found about one in five teenagers now have some degree of hearing damage. The researchers did not say why hearing loss has risen, but other experts have strong suspicions. One likely culprit, they say, is MP3 players.

    An MP3 player can be dangerous to hearing when its decibel level is turned up too high. High-decibel sounds can damage nerve endings, called hair cells. If a sound is loud enough, the damage can be permanent. A loud sound can shake the membrane (薄膜) on which the hair cells sit- “like an earthquake”. That shake can break or even uproot hair cells. When that happens, the hair cells are finished. Human ears cannot regrow hair cells. Therefore, when listening to an MP3 player, set a volume limit and avoid exposure to loud sounds.

    On the other hand, the loudness of today's music may not be totally under your control. Music companies have been purposely turning up the volume. It's a trend called the fight for loudness.

    Play a CD from the 1990s. Then play a newly released tune. Don't touch the volume control. You'll probably notice that the new CD sounds louder than the old one. Why? Sound engineers who create CDs are using dynamic range compression (压缩), a technology that makes the quiet parts of a song louder and the loud parts quieter. The overall effect of compression is a louder recording.

    Many musicians and sound engineers aren't pleased. They say that compression is driving down the quality of today, s music, making it sound flat and blaring. Gray Hobish, a sound engineer, explains that music should be a combination of loudness and softness. But music companies want to make music louder so it will stand out. That's important in the competition among recording companies.

    What about listeners? Many teenagers listen to music on the go in noisy places and through headphones, all of which reduce sound quality. So young listeners may not notice the poorer quality of modem recordings. “To their ears,” says Hobish, “the music sounds fine. And they are not aware of the hidden threat of the music they are enjoying.”

    China plans to launch 156 small satellites by 2025 to provide Internet services in low signal areas and places with adverse natural environment, according to China Aerospace Science and Industry Corporation (CASIC).

    Due to environmental conditions of deserts, mountains and seas, half of the world's population has no access to the Internet, and the information deficiency hampers local development.

    It will be China's first broadband Internet access system with small satellites hovering in low orbit, which will also help meet the needs of commercial space development.

    The project, named Hongyun, plans to send the first satellite by 2019, and launch four more by 2020. By the end of 2025, CASIC plans to have all of the 156 satellites in operation.

    The Hongyun Project, which focuses on communication, remote sensing and navigation, can offer communication and Internet services for China and less-developed 3 countries with reduced latency. Meanwhile, the project can also benefit emergency communication, sensor data collection and remote control of unmanned equipment.

    Currently, international maritime satellites are widely used in communications in mountainous areas and airplanes, but those satellites, 36, 000 kilometers above the Earth, have time and signal delay as well as high cost for providing services.

    The small satellites sent by the Hongyun Project will hover in low orbits only hundreds of kilometers to 1, 000 kilometers above the Earth, and thus could improve the Internet access. However, the low orbit satellites may face challenges in power supply, as they need more energy to reduce the influence of air-resistance compared to high orbit satellites. Experiments are needed to determine whether solar energy alone is enough.

    Once, a lioness and her cub were hunting in the jungle. The baby asked its mother, "Mother, why are we hunting when a deer is already at home?”

    The mother said, "My love! We can' t eat that deer because it has surrendered (投降) himself seeking our help. He is wounded and helpless. We must help him.”

    The baby cub was surprised and questioned again, "Why so? That's our food, we can eat it.”

    “Honey, you are right! It's our food and we can kill him in any second but do you think he deserves to be killed when he has come to-us for protection?”

    The baby cub couldn't understand her mother's vulnerability(软弱). It kept quiet and paced with its mother. At last, they didn't get anything and came back to their cave.

    The deer, on the other hand, was terrified of his own decision of taking shelter in the cave. Unfortunately he had no choice! He was attacked by a hunter and somehow managed to escape. While running for his life, he saw the cave and without a second thought entered it. He had already got a shot from the hunter. When he realized he was in the lions cave, he gave up the idea of running back again. The deer gazed at the lioness with a pitiful look, tears rolling down He sat there as if he urged for the mercy of the lioness.

    The lioness came closer to the deer, smelled it and slowly moved out of the cave with her cub.

    When the lions came back, the cub asked its mother to kill the deer again. But the lioness was firm on her decision. She said, "Sweetheart! We can-manage one night without any food. Tomorrow, I would definitely fetch out some food for you.”

    The cub said nothing, grunted(嘟哝）a little.

    When the cub slept, the lioness whispered to the deer, "Run, away from this area because I doubt if I could save you any longer if the next time situation demands!"

    The deer looked at the lioness with gratitude and slowly walked away from the cave.

    The first day my new teacher walked into our school in Spanish Harlem, I burst out laughing. Ron Clark was this young white guy from North Carolina who talked with a funny Southern accent(口音). He said he used to be a singing waiter. I thought, who is this guy? He's a complete joke.

    It was 1999 and I was in the fifth grade at New York City's P.S. 83. I guessed I'd spend most of the year in the headmaster's office. I'd always been a troublemaker. I'd get shouted at, and then the teachers would give up on me. I thought that's what would happen with Ron Clark.

    I was wrong. That first week, I kept laughing at him. He pulled me out to the hallway and said I'd better shape up(表现好). "Tamara," he said, "you're a smart kid. You can do better."

    He told me I was a natural leader and that I'd go far in life if I started studying hard. I was mad at first, but then something happened: I began to respect him. There were 29 students in our class, and it didn't take long for us to realize that Ron Clark was no ordinary teacher.

    Like most teachers, he had lots of rules: Treat each other like family. Don't cut in line. But the real difference was how concerned he was. Mr. Clark ate with us in the lunchroom instead of going to the teachers' day-room. At first, my friends and I were thinking. What is he doing?

    He asked us what was going on in our lives. Between classes, he came outside with us, and we taught him how to jump rope. When it snowed, Mr. Clark, who'd never seen snow before, threw us with snowballs, and we threw him back.

    Before coming to P.S. 83, he taught at Snowden Elementary in his hometown, Belhaven, North Carolina. His parents were DJs(流行音乐节目主持人)at dance clubs, so he grew up with music and energy. He wanted a life of adventure, he told me, but his mom encouraged him to ask for a position at Snowden when one of the teachers passed away. Mr. Clark ended up loving it. He came to Harlem because he'd seen a TV show about our troubled schools and the lack of qualified teachers. He wanted a challenge. Boy, did he get one.

    Kincaid looked at his watch: eight-seventeen. The truck started on the second try, and he backed out, shifted gears, and moved slowly down the alley under hazy sun. Through the streets of Bellingham he went, heading south on Washington 11, running along the coast of Puget Sound for a few miles, then following the highway as it swung east a little before meeting U.S Route 20.

    Turning into the sun, he began the long, winding drive through the Cascades. He liked this country and felt unpressed stopping now and then to make notes about interesting possibilities for future expeditions or to shoot what he called "memory snapshots." The purpose of these causal photographs was to remind him of places he might want to visit again and approach more seriously. In later afternoon he turned north at Spokane, picking up U.S. Route 2, which would take him halfway across the northern United States to Duluth, Minnesota.

    He wished for the thousandth time in his life that he had a dog, a golden retriever, maybe, for travels like this and to keep him company at home. But he was frequently away; overseas much of the time and it would not be fair to the animal. Still, he thought about it anyway. In a few years he would be getting too old for the hard fieldwork. "I must get a dog then." He said to himself.

    Drives like this always put him into a sentimental mood. The dog was part of it. Robert Kincaid was alone as it's possible to be—an only child, parents both dead, distant relatives who had lost track of him and he of them, no close friends.

    He thought about Marian. She had left him nine years ago after five years of marriage. He was fifty-two now, that would make her just under forty. Marian had dreams of becoming a musician, a folksinger. She knew all of the Weavers' songs and sang them pretty well in the coffeehouse of Seattle. When he was home in the old days, he drove her to the shows and sat in the audience while she sang.

    His long absences—two or three months sometimes—were hard on the marriage. He knew that. She was aware of what he did when they decided to get married, and both of them had a vague sense that it could all be handled somehow. It couldn't when he came from photographing a story in Iceland and she was gone. The note read, "Robert, it didn't work out. I left you the Harmony guitar. Stay in touch."

    He didn't stay in touch. Neither did she. He signed the divorce papers when they arrived a year later and caught a plane for Australia the next day. She had asked for nothing except her freedom.

    Most animals on land are known to us, but many living things underwater are not. Now let's get to know some of them.

    Sea cucumber

    Sea cucumber are strange animals living at the bottom of the sea. They wear brown or pale green coats with many sticks up. When summer comes, they stay deep to sleep because they are afraid of heat. And when it is autumn, they move to shallow (浅的) water and get their food.

    Pike

    The pike is a kind of freshwater fish. They are good swimmers and like swimming near boats, waiting to be fed. They have sharp teeth to catch fishes. When they are young, they live in groups. However, when they grow up, they prefer to live alone.

    Cuttlefish

    A cuttlefish can swim quite fast, so it is also called rocket (火箭) fish. It has eight arms and two feelers on its head, just around its mouth. It ejects ink (喷墨) when it is in danger. Its meat is delicious, and it is often the first choice for many people.

    Octopus

    An octopus has long arms, with which to catch food and protect itself. When it is sleeping, one or two of its arms are still on duty, keeping moving. Once it feels something dangerous, it can wake up at once to take action.