When you hear about trees cut for paper, you might think of your favorite trees in the backyard, nearby parks or wild forests being cut to pieces.

 The good news is that production and use of paper will not cause forests to disappear. Most trees used for paper come from timberlands(林地). People plant trees here for use. It usually takes 10 to 20 years for trees to grow big enough to be cut down. During that time, trees provide a home for animals and produce oxygen(氧气) for the earth. And after people cut down the big trees, they plant small ones again.

 Often, a tree is not cut down for making paper at all. People use the big part for buildings. Paper is then made from the left small part.

 We also recycle paper—People collect used paper and turn it into new products, likes boxes, newsprint and writing paper, in the factory. So it's important for us to recycle paper and reduce(减少) the amount(数量) of it in landfills(垃圾处理场).

      Astronauts are not like pilots, who fly into sky. They need some special trainings. They will fly into space. First they go to the Johnson space center in Houston Texas. They are tested there. Space doctors want to know how strong and smart they are.

      First of all, their hearts are tested. The people walk or run. Next, the space doctors see how fast their hearts are beating.

      Then it is another important test. In this test the person must curl his body up in a ball. And when he is in that position, he will be put into a round cloth bag. The doctors don't tell him how long he will have to stay in the bag. If a spaceship broke down in space, the astronauts would get into bags like these. Then they would have to wait, curled up in darkness, until they are saved. You can know that an astronaut must not be afraid of tight spaces or darkness.

      After these tests, scientists only choose the best people to start astronaut training in a training center. They will learn many other things in training. They will learn how to jump out of moving airplane, to blow up a lifeboat and get into it while they are in the ocean.

They also have to learn how to get lifted out of the ocean by a helicopter.

      When they finish training, the astronauts go on to work. They stay in good situation by running and doing exercise. They read about the special jobs. In that way they will be able to learn new facts about space travel.

      Finally, the astronaut is told to go to work on a flight into space. The members begin to know each other first. Then they can learn which jobs each will do.

    Like most people, your intelligence（智力）changes from season to season. You are probably a lot sharper in spring than you are at any time of the year. A well known scientist, Ellsworth Huntington concluded（得出结论）from other men's work and his own that climate and temperature have a clear effect on people's intelligence.

    He found that cool weather is much better for creative thinking than warm weather, but this doesn't mean that all people are not so quick at learning in summer as they are during the rest of the year. It doesn't mean, however, that the intelligence of a large number of people seems to the lowest in summer.

    Spring season appears to be the best period of the year for thinking. One reason may be that in spring man's intelligence is affected（影响）by the same factors（因素）that bring about great changes in all nature.

    Autumn is the next-best season, then follows winter. As for summer, it seems to be a good time to take long holidays from thinking.

    Some Fun and Interesting Facts

    Do you think what color oranges are? The common answer to this question is "Orange". However, the first oranges from Southeast Asia were actually green. Up to now, oranges in warmer areas like Vietnam and Thailand still stay green when they are fully grown.

    There was a man named John Chapman who planted thousands of apple trees. But the apples on those trees were much more bitter(哭的) than the ones you'd find in the supermarket today. John didn't expect has apples to be eaten whole, but rather made hard apple cider(苹果酒).

    Like most four-legged animals, cats have five toes on the front paws, but their back paws only have four toes. Scientists think they four-toe back paws might help them run faster. Do you know any other fun fact about cats?

    Walt Disney might have been the firs it gloves on his characters，as the star Mickey Mouse in 1929's The Opry House（《奥普里之屋》）.Besides being easier to interest, there's another reason why Disney did so "We didn't want him to have mouse hands because he was supposed to be more human." Disney once said.

    When we think of paper, we think of newspapers and books. But there are many other uses. Only half of the world's paper is used for books and newspapers.

    Paper is very good for keeping you warm. You have perhaps seen homeless men sleep on a large number of newspapers. In Finland, it is sometimes-40℃ in winter. The farmers wear paper boots(靴子)in the snow. Nothing could be warmer.

    Each year, more and more things are made of paper. We have had paper cups and plates for a long time. But now we hear that chairs, tables, and even beds can be made of paper. Besides paper boots and shoes, you can wear paper hats, paper dresses, and paper raincoats. When you have used them once, you may throw them away and buy new ones.

    The latest use of paper seems to be paper houses. These are not small houses for children to play in, but real, big houses for people to live in. You can buy a house with three rooms for about 500 dollars. You can put it up by yourself in a few hours, and you can use it for about five years.