In nature, you may see many insects(昆虫) and animals of different colors. Have you ever wondered why?

    Locusts are super delicious food for birds, but it is not always an easy job for birds to catch them. It is neither because locusts are good jumpers or runners nor because they are smarter than their enemies. The reason is that the colors, of locusts change with the colors of crops(庄稼). When crops are young, locusts look green. But when autumn comes, locusts change to the yellow and brown color as crops do.

    Brown bears, tigers and other animals move quietly through forests. They can't be seen easily by their enemies. This is because they have colors similar to the trees. For the same reason, polar bears that live on a land of snow and ice are white. Butterflies and bees living among the flowers are colorful like flowers. Soil insects are mostly dark colored and they live under the soil(土壤)in a dark and wet environment. However, insects with colors different from plants can easily be found and eaten by others. So in order to survive, they have to hide themselves in the daytime and appear only at night.

    Have you ever noticed some even stranger acts? The ink fish in the sea can send out some very black ink when it faces danger. As the ink spreads over, its enemies will find themselves suddenly in a dark world. At the same time the ink fish immediately swims away. That is how it keeps itself safe though it is not strong at all.

    Do you know of anyone who uses the truth to deceive(欺骗)? When someone tells you something that is true, but leaves out important information that should be included, he can give you a false picture．

    For example, someone might say, “I just won a hundred dollars on the lottery(彩票). It was great. I took that dollar ticket back to the store and turned it in for one hundred dollars!”

    This guy is a winner, right? Maybe, maybe not. We then discover that he bought $ 200 worth of tickets, and only one was a winner. He's really a big loser!

    He didn't say anything that was false, but he left out important information on purpose. That's called a half-truth. Half truths are not technically lies, but they are just as dishonest.

    Some officers often use this trick. Let's say that during Governor Smith's last term, her state lost one million jobs and gained three million jobs. Then she tries another term. One of the persons who don't support her says, “During Governor Smith's term, the state lost one million jobs!” That's true. However, an honest statement would have been, “During Governor Smith's term, the state had a net gain of two million jobs.''

    Advertisers will sometimes use half—truths. It's against the law to make false statements so they try to mislead you with the truth. An advertisement might say, “Nine out of ten doctors advised their patients to take Yucky Pills to cure toothache. ”It fails to mention that they only asked ten doctors and nine of them work for the Yucky Company.

    This kind of thing happens too often. It's a sad fact of life: Lies are lies, and sometimes the truth can lie as well.

    All living things on the earth need other living things to live. Nothing lives alone. Most animals must live in a group, and even a plant grows close together with others of the same kind. Sometimes one living thing kills another, one eats and the other is eaten. Each kind of life eats another kind of life in order to live, and together they form a food chain (食物链). Some food chains are simple, while others are not. But all food chains begin with the sun, and all food chains become broken up if one of the links (联系) disappears.

    All life needs sunlight to live on. But only plants can use sunlight directly (直接). Plants are “factories”. They make food from sunlight, water and things in the soil (土壤) and air.

    Plants feed all other living things. Animals can only use the sun's energy (能量) after it has been changed into food by plants. Some animals feed directly on plants, others eat smaller animals. Meat-eating animals are only eating plants indirectly.

    What about human beings? We are members of many food chains. We eat wheat (小麦), rice, vegetables, fruits and so on. We also eat meat and drink milk. But humans often break up the food chains. They kill wild animals. They also make rivers, lakes and seas dirty. When these rivers, lakes and seas are polluted, the fish in them cannot be eaten. If men eat the fish, they will get strange diseases (疾病).

    Each form of life is linked to all others. Breaking the links puts all life in danger.

    My mother used to ask me what the most important part of the body was. I got different answers at different ages.

    When I was young, I thought sound was very important to us, so I said, "My ears, Mum. "But she shook her head and said no. Several years passed, and she asked me again. I believed that I got the right answer after thinking it over. So I told her，"Sight is very important to everyone, so it must be our eyes. "But she told me I was wrong. I tried many times after that, but her answer was always the same. Till last year, my grandma died. Everybody was crying, and everybody was hurt. My mom looked at me and asked me with tears in her eyes，"Do you know the answer now？"I was surprised when she asked me this question then. "My son, the answer is your shoulder. Everyone needs a shoulder to cry on. "

    Finally, I realized (意识到)all she hoped is that I can have enough love and friends so that I will have a shoulder to cry on when I need it.