On June 26th, 2000, two scientists, called Francis Collins and Craig Venter, told the world that they could now read the whole “map” of the human body: DNA. DNA is something that all humans have, and it tells the body what to do. DNA is the reason that we look like our mother and father, because we get some of their DNA to make our own. Now we can read some of this “map”, and so we can find out more about how our bodies work.

    People have been trying to understand the human body for a long time. In 1860, Gregory Mendel discovered that there is a special reason why we look the same as other people in our family. It is because of small things called “genes” that we have in our body. In 1953, James Watson and Francis Crick made another discovery and found out that those small parts are really messages written in the DNA with a special language.

    In 1961, Marshall Nirenberg and Johann Matthaei found the first “word” that they could understand in that language, showing how DNA tells the cell to build its parts. This meant that one day we would be able to read all the messages that a human body gets from its parents' bodies. Scientists have now found all the words in DNA map, but we still do not understand what they all do. By understanding what just one “word” means, we can help save people from several diseases. So the more we understand, the more doctors will be able to do.

    Most people hope that this will help to make better medicine and help people who are very ill. Other people worry about that when we learn more words and find out lots of other information, we still use it in the wrong way, just to make people more attractive, or stop sick people getting jobs.

    Which of your two hands do you use 1 ? Very few of us can use 2 of our hands equally(相等地) well. Most of us are 3. Only about five people out of 4 hundred are left-handed. New-born babies can take things 5 either of their hands, 6 in about two years most of them use their right hands. Scientists(科学家) don't know 7 this happens. Scientists 8 that monkeys like to use one of their hands more than the other, but it can be either hand. Most of people use their right hands better and this makes life 9 for those left-handed persons. We live in a 10 world.

    We all know that many inventions have changed our life a lot. They play important roles in our daily life. Here are some interesting inventions.

    There are many colours in nature. But do you know if a colour has weight? I think you'll say "no". But I am afraid you are wrong. If you don't believe, you may do a small experiment.

    First, put two objects with the same weight into two boxes. Then, cover the box. Third, wrap(包裹) one box with a red piece of paper, the other with a white piece of paper. OK. Now hold the boxes with your hand one by one. It is certain that you will think the red one is a little heavier. Why do you think so? A scientist found that different colours have different weight in a man's mind. So he did many tests and at last he got the result. That is to say, every colour has its own weight in our mind and their order(顺序) is the same. The heaviest colour is red, then blue, green, orange, yellow and white.

    The scientist told us that colours also have smell. Can you smell the colour? Of course not. Then why did the scientist say so? That is because every colour stands for a kind of light with a certain wavelength (波长). It reaches our brain(大脑) through sense organs(感觉器官).

    According to this discovery, scientists say that people accept the colours they like, and refuse the colours they hate. So your body and mind will be healthy by using the colors you like. Or you'll be nervous or even get ill. For example, if you stay in a room with red windows, wallpapers and furniture for two hours, you'll feel you have been there for four hours. But if the room is blue, you'll feel you have been there for only an hour. Another example, if a person walks out of a red room and into a blue room, his temperature will fall. That means our body temperature will change with different colours.