Many years ago when people had no thermometres (温度计), they usually touched a thing to see how hot or cold it was. The following experiment shows how easy it was to make a mistake.

    Take three glasses: the first one with very hot water, the second one with very cold water, and the third one with water at room temperature. Then you put a finger of one hand in the hot water, and a finger of the other hand in the cold water. You hold your fingers in the two glasses for a minute. Then you use each finger, one after another, to see how hot or cold the water in the third glass is. You will find that the water is warm to the finger that was in the cold water before, but the finger which was in the hot water will feel cold in the same glass of water.

    That is why you must always find the temperature in a scientific way. You must not try to tell the temperature as it seems to you.

    You will often make a mistake if you take something that seems to you for real fact. For example, when you are going to an amusement park by bus and you want to get there very quickly, it seems to you that your bus is going very slowly, slower than the other buses. But if it is Sunday and you have much free time, it seems to you all the buses and cars are going very fast.

    How do you remember the way to your house? Where do dreams come from? It is your brain that does these things. A British scientist showed that "sleep can improve one's memory". It's not a dream for students to study when they sleep. In fact, your brain is working day and night. If you learn words before bed, a certain part of the brain may help you to remember the words while you are sleeping. What's more, another scientist in the U. S. A. found that there was a "talent button (天才按钮)" in the human brain. It might make a person more talented.

    There are more interesting things about the brain. Your brain uses less energy than a fridge light. Just two bananas can give the brain enough energy to work for a whole day. According to some scientists, yawning (打哈欠) keeps our brain "cool", which makes us think quicker.

    Here are some pieces of advice to keep a good brain:
    ·Eat healthy foods.

    ·Get lot of playtime or exercise.

    ·Don't drink or smoke.

    ·Use your brain a lot.

    Bruce shook his money box again.

    Nothing! He carefully counted the coins that lay on the bed. All that he had was $24.52. The 1 which he wanted was at least $90. How on earth(究竟)was he going to get the rest of the 2?

    He knew that his friends all had bicycles. It was hard to hang out(闲逛)with people when you were the only one 3 a bicycle. He thought about 4 he could do. He couldn't get money from his parents, because he knew they had no extra(额外的)money.

    There was only one way to get money, and that was to earn(挣钱)it. He would have to find job. He decided to ask Mr Clay for 5. "Well, you can start right here," said Mr Clay. "You see, my windows need cleaning and my car needs washing."

    That was the beginning of Bruce's part-time job. For the next three months he worked every day after finishing his homework. He took dogs for walks and cleaned rooms.

    The day finally came when Bruce 6 his money and found $94.32. He wasted no time and went down to the shop to 7 the bicycle he wanted. He rode home proudly, looking forward to 8 his new bicycle to his friends. Bruce liked his bicycle very much because he had bought it with his own money. At last, his dream came true, and his parents were proud of him.