Dear human beings,

    Hi! I'm 80 years old now. So I've seen 1 of the world. We've lived on Earth with you thousands of years. Each day we release(释放) O₂ and remove harmful gas so that you have fresh 2; we help prevent the Earth's soil（土壤）from being washed away, and above all, we give all kinds of fruits, nuts, beans as well as 3 to you.

    We are now in great 4 because of you. You are killing us at a terrible speed. You are burning and cutting down millions of us each year, but you're not 5enough. For every tree being planted today, 30 trees are being cut down. What would you do if all of us 6? Perhaps you would die, too.7 us, you wouldn't get enough material for buildings, furniture（家具）, paper products, and your cities would 8ugly. Moreover, air pollution and noise pollution would become more and more serious, and your life would become nasty.

    The 9 thing for you to do now is to stop your bad manner. We are the best fighters 10 pollution and we are your best friends!  

Your friend,

An old tree

    How could we live without the Internet? That's1most of us keep in touch with friends, find cool places to visit, or get the latest2. We can use it to do homework, find out what new movies are on, get information3a college (大学) we're thinking about, or find a job. Almost(几乎)4we can think of has a website about it.

    5you've heard stories about people who are cheated(被骗) in chat rooms. Some users don't tell others their true names. Everyone in the chat room looks like6a mask(面具). Some people may want to do something7in it. They will sometimes ask visitors for their information. The information might be about their families, or where they8. It shouldn't be given away. This might9you or your family.

    Of course, the Internet is home to millions of places you can and should visit. However, remember to10yourself while online.

    It was a fine spring day for a walk down the street. A mother and her two little girls walked along the sidewalk, happily laughing. 1 , hundred small alien ships appeared on the horizon. It started 2off some electric rays. People screamed. Children cried. There was 3 everywhere.

    There came the tingling sound of glasses, breaking everywhere. People fled in every 4. The mother was jostled(推) and lost hold of her5. She raced around shouting and crying for her kids. She thought they were lost to her forever.

    The sky cleared up. The aliens were 6. But there was no sight of the children. Heart-broken, the mother reached her house, crying her eyes out.

    She heard someone 7 "Mamma". Was it her kids? She frantically(发狂似地)8 around. There they were! Hand in hand they came running towards her. She ran towards them too. Her arms stretched out 9 to hug them. She opened her eyes. The pillow was wet. It was a dream!

    She raced to the kids' bedroom. Her lovely girls were sleeping peacefully. She kissed both their foreheads and 10"love you".

    Can you imagine that we could build a beautiful city with rubbish? Maybe you will think it is1. However, it can be true! Nothing is a waste if we have a creative mind. Let me show you something about 2rubbish.

    Sometimes we can see tons of rubbish in the streets, on the roads, near the buildings... here and there.  Many large cities became so ugly 3 it. Nobody likes rubbish, but in fact, some rubbish can be used again. All of us want to solve the problem, we must do something to 4 rubbish. We should take action from now on. 5, some good things will not be wasted.

    Do you often throw away things you don't need any more? Have you ever thought about how these things can actually be put to good use? For Example, when a car gets too old, it may not run any more. But we can use the metal of the car to make something else. When a bottle is empty, it 6 as waste. You don't know bottle glass can be made into sand and used to build streets. Rubbish7food can be changed into fertilizer to make plants grow better. It is cheap and safe. And other rubbish can also be used to make building blocks. Now, 8machines are designed for that.

    9, people will watch films in a beautiful cinema which is built out of rubbish. Besides buildings and roads, cities may be made from rubbish. But so far, building beautiful cities made from rubbish is only 10.

    There have been many great inventions that change the way we live. The first great 1was one that is still very important today-the wheel. This made it easy for man 2heavy things and to travel long distances. For hundreds of years after that, there were 3inventions that had as much effect as the wheel. Then in the early 1800's the world started to change 4. There was little unknown land left in the world. People did not have to explore much anymore. In the second half of the 19th century many great inventions were made.      5them were the camera, the electric light and the radio. These have all become a big part of our life today.

    The first part of the 20th century saw more great inventions. The helicopter in 1909. Movies 6sound in 1926. The computer in 1928. And jet planes in 1930. This was also a time when a new 7was first made. Nylon came out in 1935. It changed the kind of clothes people wear. Of course new inventions continued to be made. Man began looking 8 ways to go into space. Russia made the first step. Then the United States took another. Since then other countries，including China and Japan,9their steps into space. In 1969 man took his biggest step away from earth. 10first walked on the moon. This was certainly just a beginning. New inventions will someday allow us to do things we have never yet dreamed of.

    Global warming means the temperature of the Earth is getting higher and higher. If the Earth gets 1, some of the following things could happen:

    The sea level could 2 because of the melting of sea ice.

    Many animals that live on the ice might 3 out.

    There could be more floods(洪水), 4 near the sea and rivers.

    Some plants and animals might die because they cannot live in high 5.

    Global warming is a very 6 problem now. There is something we can do to help to slow it down.

    Scientists have been studying global warming for years. They have found that some things that people do in everyday life make much gas that 7 global warming. One big cause of this is the burning of oil, gas and coal for energy for our cars and homes. This gives off too much greenhouse gas. We can do something to cut 8 on the amount of greenhouse gas.

    ⒈ We can really help by using less energy in life, and less gas in our family cars. We should turn off the 9 and turn down other electrical equipment. We should walk more and use cars less.

    ⒉ 10 can take in some of the greenhouse gas. So we should plant more trees.