Let's try doing the following experiment.

 What to do：

 Use string to hang a paper clip or other small object at about chest（胸部）level.

 Pick up a stick，such as a broom handle. Take three or four steps away from the paper clip.

Now close one eye and walk toward the paper clip. Try to touch it with the tip of the stick. If you miss，try again，still keeping one eye closed. Now try it with both eyes open and see if it's easier to do.

 How it works：

 In the experiment，you have to judge how far away the paper clip is. Your brain has several ways of doing this.

 One simple way depends on how much your eye has to focus（聚焦）itself. Using only one eye，most people will find it difficult to touch the paper clip on the first try，but the brain still gets some information about distance—though not much.

 Your brain can judge distance much better when you look at something with both eyes. In fact，your brain has more than one way to use both eyes in judging distance. For example，to see anything clearly，you have to make both of your eyes point at the object. When you look at a nearby object，your eyes turn inward. You can feel this happening if you look at the tip of your finger and move your finger toward your nose.

 Your brain gets information from the eyes about how much they are pointing toward each other. Using that information，the brain can tell how far away any object is，whether it is a basketball or a paper clip.

      We want to explore and try to better understand the world in which we live. Space exploration is one of the ways.Through the exploration of space, we can begin to unravel the mysteries of our universe, and to better know our living environment.

      Space exploration provides us with knowledge about the beginning of our solar system, our own planet and ourselves. It also helps answer the questions that have puzzled us for many years. Solar system exploration is important because it is good for us.

      Space technology has become an important part of our daily lives. Some technology uses satellites to communicate. Satellites are also used to examine the changes in the Earth's climate and seas, for weather report and for military. We also use satellites in food production. Because of the use of space technology in crops, fewer and fewer people will suffer hunger.

        The space program provides a chance for nations to work together. The cooperation(合作) promotes peace and understanding between governments and their people. Many governments have taken part in the space technology, including the United States, Russia, Japan, the European nations and India. In the near future, other nations will take part in it. In fact, the United States remains the leader in new space technology.

    Life in the future will be different from life today.

    The population(人口) is growing fast. There will be more people in the world and most of them will live longer.

    Computer will be much smaller and more useful, and there will be at least one in each home. And computer science will be one of the most important subjects in school then. 

    People will work fewer hours than they do now, and they will have more free time for sports, watching TV and travel.

    Our food will be different, too. More land(土地) will be used for building new towns and houses for people. So there will be less land for cows and sheep, and meat will be more expensive. Maybe no one will eat it one day. They will eat more fruits and vegetables. 

    Work in the future will also be different. Robots will do dangerous and hard work. Because of this, many people will have no jobs to do. This will be a big problem in the future.  

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