Living in the wild can be hard. Finding food and staying safe aren't easy. Each day, animals struggle to survive in their habitats. Not all animals get by on their own. Some animals form a close partnership with other kinds of animals. These pairings are called symbiotic (共生的) relationships.

    In a symbiotic relationship, the animals depend on each other. One animal helps the other meet its needs. Sounds good, right? Not always. Some animals are not very kind to their partners. In some cases, one animal meets its needs but hurts its partner. Take ticks, for example. These insects suck blood to live. To get blood, they attach themselves to other kinds of animals. Ticks can pass germs that cause disease instead of helping their hosts.

    In other relationships, animals don't treat their partners so poorly Both animals benefit from living with the other animal.

    Small animals called cleaner shrimps have found a way of helping fish at coral reefs. As their name suggests, the shrimps clean the fish. They hang out at what scientists call a cleaning station. A fish stops by. Then a shrimp climbs onto the fish and even steps into the fish's mouth. The shrimp uses its tiny claws to pick stuff off the fish's body. That can include dead skin, tiny pieces of food, and wee creatures that can hurt the fish. The fish gets a nice cleaning. The shrimp enjoys a tasty meal offish trash.

    Small birds called plovers are also in the cleaning business. They have big customers—crocodiles. Crocs have long snouts（鼻子）filled with sharp teeth, Cleaning them is tricky. When a croc opens its mouth, the plover hops right in. The croc does not snap its snout shut. Instead, it lets the plover eat small, harmful animals attached to its teeth. The plover gets an easy meal while the croc gets clean teeth.

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When I was nine years old, I loved to go fishing with my dad. But the only thing that wasn't very fun about it was that he could catch many fish while I couldn't catch anything. I usually got pretty upset and kept asking him why. He always answered, "Son, if you want to catch a fish, you have to think like a fish." I remember being even more upset then because, "I'm not a fish!" I didn't know how to think like a fish. Besides, I reasoned, how could what I think influence what a fish does?

    As I got a little older I began to understand what my dad really meant. So, I read some books on fish. And I even joined the local fishing club and started attending the monthly meetings. I learned that a fish is a cold-blooded animal and therefore is very sensitive to water temperature. That is why fish prefer shallow water to deep water because the former is warmer. Besides, water is usually warmer in direct sunlight than in the shade. Yet, fish don't have any eyelids(眼皮) and the sun hurts their eyes…The more I understood fish, the more I became effective at finding and catching them.

When I grew up and entered the business world, I remember hearing my first boss say, "We all need to think like salespeople." But it didn't completely make sense. My dad never once said, "If you want to catch a fish you need to think like a fisherman." What he said was, "You need to think like a fish." Years later, with great efforts to promote long-term services to people much older and richer than me, I gradually learned what we all need is to think more like customers. It is not an easy job. I will show you how in the following chapters.

    Killer whales in Alaska's Bering Sea have figured out an easy way to get fed. Instead of seeking out the fish them- selves, the clever whales chase down fishing boats and steal the entire catch of the day, as much as 20,000 to 30,000 pounds.

    Killer whale “thieves” are not a new phenomenon. Japanese fishermen have reported being followed by killer Whales since the 1950s. However, the increasing frequency of whale fish theft in the Bering Sea's continental shelf is now threatening the livelihood of fishermen.

    Paul Clampitt, a local fisherman, says his crew tried to keep the whales away with loud sounds. Though that worked for a short time, the whales now consider the noise “ a dinner bell”. Jay Herbert tried using sonar to keep the whales away. He also met with little success. According to the experienced fisherman, the smart whales deliberately seek out longliners (延绳钓渔船）, and, all the first opportunity presented to them, steal the fish, leaving behind just the lips of the fish caught!

    NOAA Fisheries biologist John Moran is not surprised at the whales' thieving skill. The expert says whales are skilled hunters who can distinguish the sounds of different boats and even recognize the sounds of the operating system that places the fishing equipment into the ocean. The expert jokes, “ Grabbing a fish off a line is nothing.” Since they are social animals, it is easy for whales to pass their skills on to others.

    Killer whales are not the only whale species that have learned to steal from humans. In the Gulf of Alaska, sperm whales also conduct similar thefts. Longline fishermen off Washington, Chile, Australia, Hawaii, and many other countries have reported similar incidents. There is, unfortunately, no easy fix to this problem. One of the possible solutions is using pot traps similar to the ones used to catch crabs. However, the cost of switching from longline to pot fishing is too high, especially for small-scale fisheries. There is also no guarantee that the catch will be safe from the intelligent whales which, many fear, will eventually figure out how to open the pots!

    One of the most important things in the world is friendship. In order to have friends, you have to be a friend. But how can you be a good friend at school？

Listen﹣Listen when they are talking. Don't say anything unless they ask you a question. Sometimes it's not necessary for you to have anything to say; they just need someone to talk to about their feelings.

    Help them﹣If your friend is ever in need of something, be there to help them. You should try to put them first, but make sure you don't do everything they want you to do. Try to take an extra pencil or pen with you to classes in case they forget one. Have a little extra money in your pocket in case they forget something they need.

    Be there for them﹣Be there for your friends to help make them feel better in hard times. Marilyn Monroe, a famous U.S. actor, once said, "I often make mistakes. Sometimes I am out of control, but if you can't stay with me at my worst, you are sure not to deserve to be with me at my best." Always remember this! If you don't want to stay with your friends when they're in hard times, then you don't deserve to be with them when they're having a good time!

    Make plans﹣Try to make plans with your friends. Go shopping, go for ice cream, have a party, go to a movie and so on. Take time to know each other even better by doing something you both enjoy. By planning things together, you both can have a good time. And you'll remember these things when you're all old!

    Mary Lyon was a leader in women's education in the nineteenth century. It was a time when women's education was not considered important in the United States. States did require each town to provide a school for children, but there were not enough teachers. Most young women were not able to continue their education. If they did, they often were not taught much except the French language, how to sew clothing, and music.

    Mary Lyon felt that women's education was extremely important. She believed women were teachers both in the home and in the classroom. Mary opened a school for young women in the village of Buckland. She suggested new ways of teaching, including holding discussion groups for students.

    Then, Mary began to raise money for her dream school for the higher education of women. This school would own its own property (财产), guided by an independent group of direction. Its finances would be the responsibility of the directors. It would not depend on any one person to continue. And, the students would share in cleaning and cooking to keep costs down. In 1837, Mary Lyon opened Mount Holyoke Seminary for Women. In 1893, 34 years after her death, under a state law, Mount Holyoke Female Seminary became the first college to offer women the same kind of education as men.

    Mary's efforts led to the spread of higher education for women in the United States. Her influence lasted as the many students from her schools went out to teach others.

Although a few recreational snowmobilers (驾驶摩托雪橇者) destroy ecosystems as they ride through the wilderness, most snowmobilers love and respect America's natural heritage. That's why they brave the cold to explore what is left of wild America — including Yellowstone National Park. Unfortunately these snowmobilers are unconsciously damaging what they love. Because snowmobiles in the park not only create both air and noise pollution but also strains (使紧张) the already tight budget of the park service, recreational snowmobiles should be banned from Yellowstone National Park.

It may be hard to imagine that about 1,000 snowmobiles a day could lead to air pollution in a park half the size of Connecticut, but in fact they can. In addition to polluting the air, snowmobiles are noisy, disturbing the peace and silence that park visitors have a right to expect. One study reports that twelve snowmobiles traveling together could be heard as far as two miles away. Such noise affects the park's wildlife.

Funds that should be used to preserve Yellowstone National Park and its wildlife have been used to deal with the snowmobile issue. Also, park rangers are spending an increasing amount of their valuable time policing snowmobilers, which takes away from park rangers' primary responsibility—preserving this country's treasured natural resources.

Opponents of a ban argue that a central mission of the park service is to provide access to national parks. Admittedly, winter access is important, but ordinary people can enjoy the park by means other than snowmobiles. Also, the park service's mission is not just to provide access to the parks; no less important is its mission to preserve the parks' pristine natural resources for future generations.

Even with a ban on snowmobiling in the park itself, the Yellowstone area would still earn the title of Snowmobiling Capital of America. All of the streets of West Yellowstone, the area's major town, are open to snowmobilers, and many trails run out of the town. As to Yellowstone National Park, a ban on snowmobiles would allow the park service to devote more of its limited resources to one of its primary missions: the protection of natural resources. Visitors would still be able to appreciate Yellowstone's beauty— its geysers, its wildlife, and its snow-covered vistas —throughout the park's long winter.