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    There is a lake near a forest in Sweden. The water in the lake is very clear and everything is quiet and still. On the far side of the water is some farmland and further away, across the field, is an old church built on a hill. It has just stopped raining. The brook(小溪) flowing into the lake is full and there is still some half-melted(半融化的) snow from last winter on the ground.

    The reason the water is so clear, and everything is so quiet and still, is that most of the plant and animal life in and around the lake is dead. There are no birds because all the fish and insects, which the birds need for food, have disappeared. Many trees in the forest are losing their leaves and bark (树皮), and are sick and dying. Others were blown down by the high winds of last winter. A farmer is working in a field planting something, but unless he plants a stronger kind of seed this year, the crop will be between 25 to 40 percent lower than a few years ago. The stones of the old church tower are turning to powder and unless the tower is repaired soon, it will fall down.

    All the death and destruction(破坏) in this place is caused by the smoke coming out of factories and poisonous gases from cars and trucks. And yet this silent lake is hundreds of meters aways from the nearest factory and highway.

    Can dolphins talk? Maybe they can't talk with words, but they talk with sounds. They show their feelings with sounds.

    Dolphins travel in a group. We call a group of fish“a school(一群)。” They don't study, but they travel together. Dolphins are mammals(哺乳动物)，not fish, but they swim together like fish in a school.

    Dolphins talk to the other dolphins in the school. They give information. They tell when they are happy or sad or afraid. They say” welcome” when a dolphin comes back to the school. They talk when they play.

    They make a few sounds above water. They make many more sounds under water. People cannot hear these sounds because they are very, very high. Scientists make tapes of the sounds and study them.

    Sometimes people catch a dolphin for a large aquarium(水族馆). People can watch the dolphins in a show. Dolphins don't like to be away from their school in an aquarium. They are sad and lonely.

    There are many stories about dolphins. They help people. Sometimes they save somebody's life. Dolphins' meat is good, but people don't like to kill them. They say that dolphins bring good luck. Many people believe this.

    In northern China during spring, big sandstorms often make trouble for people. When the sky is dark with sand, buses and cars all move much more slowly. Sometimes, people can't even see for 20 metres.

    Sandstorms usually happen in spring. Big sandstorms happened in more than 10 provinces in northern China last year. More than 70 million people have had problems in those places because of the sandstorms.

    People in southern China don't have to worry about this kind of bad weather. Most of the sand comes from the north of China. In northern China, lots of places have few trees and don't get much rain. People there have been cutting down too many trees. When there aren't many trees, the ground can't keep enough water. Over the years, the ground dries up and turns to sand. When spring comes and the ice melts (融化), the ground becomes looser (更松散的). Strong winds take the loose sand into the sky.

    Sandstorms are bad for people's health. If people take in too much sand, they could cough or have asthma (哮喘).

    Sandstorms also give farmers lots of problems. Sometimes their sheep get lost in the storms and never get back home. The winds also tear down farmers' houses.

    What can you do to stop sandstorms? Here's an idea: Ask your parents to help you plant some trees this spring.

    If you see people cutting down too many trees, tell them about the dangers of sandstorms, and ask your government to stop them from cutting.

    In the universe, as we know, there is the Sun, the moon, the Earth and a good many stars. Through our geography lessons, we know the Earth goes around the Sun, and the moon goes around the Earth. We have day and night because the Earth keeps turning all the time. When our part of the Earth turns to the Sun, it is day. When our part of the Earth turns away from the Sun, it is night.

    Just because the moon is closer to the Earth than the Sun, it looks much bigger than the Sun. Big things will look smaller when they are farther, and small things also look bigger when they are nearer.

    The Sun is bright enough to give out very strong light. The moon can't give any light at all, but it looks quite bright, too. Why？In fact, the light from the moon comes from the Sun. The moon looks much bigger and brighter than the stars. But actually (事实上) the stars are much bigger and brighter than the moon. They look smaller than the moon also because they are farther away from the Earth.

    There are still many other planets in the universe. But of all these planets, only on Earth there are living things and people can only live on Earth, too. But at 9∶00 am on October 15th 2003,Chinese astronaut Yang Liwei was set up to space. He stayed there for 21 hours. It was the first time for Chinese to get into space.

    Many students think that learning a new language is very difficult. But if your brain (大脑) is only the same size as a bird's, you will know how difficult it is to learn English. That is what some birds can do.

Many birds can copy (模仿) the sounds of language. A type of African parrot is very good at doing this. This kind of parrot has grey feathers and people say they are clever.

Every December in London, the National Cage and Aviary Bird Show tries to find the best "talking" bird in the world. One bird named Prudle stood out (突出) among the " talking birds"  by winning this prize every year from 1965 to 1977. In 1958, somebody took Prudle from his nest in Uganda, and then sold it to a woman named Iris Frost. She then took care of him at her home in Seaford, England. Before he died in 1994, aged 35, Prudle knew almost 800 words in English. Prudle was also the oldest bird in the world that lived in a cage.

Another parrot named Puck was tested in 1993. It turned out that Puck knew even more words than Prudle. Puck knew more than 1,700 English words. In the 2003 Guinness Book of World Records, Puck was listed as knowing more words than any other bird in the world.