There are many colors in nature. But do you think that a color has weight? I think you'll say 6/no". But I'm afraid you are wrong. If you don't believe it, you may do a small experiment(实验).

  First, put two objects with the same weight into two boxes. Then cover the boxes.Third, wrap(包裹) one box with a red piece of paper, the other one 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 colors have different weights in man's mind. That is to say, every color has its own weight in our mind.

 The scientist told us that colors also have smell. Can you smell the color? Of course not. Then why did the scientist say S07 That is because every color stands for (代表) a kind of light with a certain wavelength,(波长). It reaches our brain through sense organs

 According to this discovery, scientists say that people accept the colors they like, and refuse the colors 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 (例如) ,  you like blue and hate red.  If you stay in a room with red windows, wallpaper and furniture（家具) 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.  And, if a person walks out of a blue room and into a red room, his temperature will rise.That means our body temperature will change with different colors.

There is little rain in desert. Because deserts are so dry, they have no "quilt" to help stop the soil from going away. As a result, they may get very hot during the day with the sun shining, but don't hold the heat overnight. Many deserts can quickly get cold once the sun goes down. Some deserts can reach temperatures of over 100 degrees F during the day and then drop below freezing (32 degrees F) during the night.

The largest hot and dry desert in the world is the Sahara Desert in Northern Africa. The Sahara is a sandy desert with great sand hills. It covers over 3 million square miles of Africa. Other large deserts include the Arabian Desert in the Middle East, the Gobi Desert in Northern China and Mongolia, and Kalahari Desert in Africa.

Animals that live in the desert are also used to needing little water. Many get all the water they need from the food they eat. Other animals keep water that they can use later. The camel stores up fat in its hump while other animals keep something they need in their tails.

Only certain types of plants can live in the terrible environment of the desert. You won't see a lot of tall trees in the desert. Most plants have a way to keep water in their leaves, or trunks so they can live a long time without water.

Now deserts cover around 20% of the world's land, but they are growing. This is called desertification and is caused by different reasons including human activities. The Sahara Desert is growing larger and larger each year. What should we do with it ?

    Have you ever heard someone use the phrase"once in a blue moon"？People use this expression to describe something that they do not do very often．For example，someone might say that he tries to avoid eating sweets because they are unhealthy，but will eat chocolate"once in a blue moon"．Or someone who does not usually like to go to the beach might say"I visit the shore once in a blue moon．"While many people use this phrase，not everyone knows the meaning behind it．

    The first thing to know is that the moon itself is never really blue．This is just an expression．In fact，the phrase"blue moon"has to do with the shape of the moon，not the color．

    As the moon travels around the earth，it appears to change shape．We connect names with certain shapes of the moon．For example，when we can see a small part of the moon，it is called a crescent moon．A crescent is a shape that looks like the tip of a fingernail（指甲尖）．When we cannot see the moon at all，it is called a new moon．When we can see the whole moon，it is called a full moon．Usually，there is only one full moon every month．Sometimes，however，there are two full moons in one month．When this happens，the second full moon is called"a blue moon"．

    Over the next 20years，there will only be 15blue moons．So you can seldom see a blue moon． This fact has led people to use the expression"once in a blue moon"to describe things they don't often do in their lives．

    Have you ever had the strange feeling that you were being watched? You tum around and, sure enough, someone was looking right at you!

Parapsychologists(R y3)say that humans have a natural ability to sense when someone is looking at them. To research whether such a "six sense" really exists, Robert Baker, a psychologist(心理学家) at the University of Kentucky, did two experiments.

    In the first one, Baker sat behind unknowing people in public places and stared at the backs of their heads for 5 to 15 minutes. The subjects(受试者)were eating, drinking, reading, studying, watching TV, or working at a computer. Baker made sure that the people could not tell that he was sitting behind them during those periods. Later when he questioned the subjects, almost all them said they had no sense that someone was staring at them.

    For the second experiment, Baker told the subjects that they would be stared at from time to time from behind in a laboratory setting. The people had to write down when they felt they being stared at and when they weren't. Baker found the subjects were no better at telling when they were stared at and when they weren't.

    Baker concludes that people do not have the ability to sense when they are being stared at. If people doubt the outcome of his two experiments, said Baker," I suggest they repeat the experiments and see for themselves

    My parents often take me to the zoo at weekends. I like animals. I have many toy animals in my room. In the zoo I can see tigers, elephants, pandas and many other animals. Some animals are friendly, but some are not. Tigers, lions and snakes are dangerous. That is why they have to be in the cage. But I think it is terrible for animals to be in the cage.

    Tigers usually live in forests and mountains. They can run. They catch and eat small animals, but now they live in small rooms. They can only walk and sleep in the cages, and they want to go out. I feel sorry for them.

    I think my favourite animals are dolphins. I like watching them swim and jump. They can play with a ball. They can "walk" on the water! They are very friendly to people. They can help you when you fall into water and can't swim.