Do you know why different animals or pests have their special colours? Colours in them seem to be used mainly to protect themselves. Some birds love eating locusts (蝗虫), but birds cannot easily catch them, why? It is because locusts change their colours with the change of the colours of crops. When crops are green, locusts look green. But as the harvest (收获) time comes, locusts change to the same brown colour as crops have. Some other pests with different colours from plants are easily found and eaten by others. So they have to hide themselves for living and appear only at night.

    If you study animals' life, you'll find the main use of colour is to protect themselves. Bears, lions and other animals move quietly through the forests and they cannot be easily seen by hunters. This is because they have the colours much like the trees.

    Have you ever noticed an even stranger act? A kind of fish in the sea can send out a kind of very black liquid (液体) when it faces danger. While the liquid spreads, its enemies cannot find it. And it immediately swims away. So it has lived up to now though it is not strong at all.

    Is it good to be in a middle school? Most American children think so. In America, middle schools often have sixth, seventh, and eighth grades. It is different in different places.

    For children, going to a middle school is a big change. Most middle schools in America have a special day for new middle school students. On that day, they are showed around the school by their new teachers. And they could know a lot about the history of the school. They also would make friends with the old schoolmates (校友).

    They will grow up and learn some different and difficult things in a middle school. A new middle school student will learn foreign languages, computer, music and art, health, and other skills, such as cooking.

    A middle school will have sports teams, clubs and have activities for children. They can choose what they like and join them. If they are good at singing, playing basketball or something else, or if they want to learn, they can join them. Most American children think it's good to be in a middle school.

    Dragon Boat Festival is a fun Chinese holiday. Usually, it's in June or July. Both children and adults（大人）like this holiday.

First, there are dragon boat races. Dragon boats are very long. They have bright colours, In each boat, there are many people rowing（划）. There's also somebody beating a drum（击鼓）. The winners（获胜者）of the races can get a lot of money.

During Dragon Boat Festival, people also eat a special kind of food-rice dumplings. To make these dumplings, people prepare（准备）many things. Then they can make different flavors of dumplings. Some are sweet（甜的），some are salty（咸的）. They all taste good. People give them to friends.

On the evening of the holiday, families have a big meal together. Dragon Boat Festival is a great time for everybody.

Many people take running as a way to keep fit. They like to run in hot weather and enjoy the feeling of being wet through with sweat (汗) while running. Cold weather during winter months, with low temperatures and freezing cold winds, may keep people from running in the open air.

However, a new study shows that the drop in temperature is a good reason to run. In fact, running in cold weather helps improve one's performance. Many runners might find it easier to run in winter than in hot weather. The body needs less water on a cold day than in warm weather. In addition, lower temperatures reduce stress on the body. When you run in cold weather, your heart rate is lower.

John Brewer is a professor of applied sports science at St. Mary's University in London. For this study, he and other researchers put a group of people into a room where summer and winter weather conditions are recreated. The test subjects were asked to run 10,000 meters under both conditions and their biological measurements were recorded and studied.From the study, every movement runners make produces heat. The heat can be really damaging unless the body can lose it. One way in which people lose heat is by sweating. The body loses heat through sweat. The body also loses it by transporting the blood to the surface of the skin and it puts more stress on the heart, especially in hot conditions because it's much harder to lose heat when the outside environment is warm. As the result shows, running in hot temperatures results in 6 percent higher heat rates.

When running in cold conditions, the body does not have to work hard to move blood to the skin surface. Therefore, it requires less energy. The most important thing for people who run in cold conditions is to wear the right clothing. Keep as dry as possible when exercising in low temperatures. Wear warm and light clothing to keep sweat away from your skin. So don't let winter weather keep you indoors. Simply get ready for the low temperatures and start running.

Have you ever heard of the "space race (太空竞赛)"? It sounds like a game, but it was not. The "space race" was a kind of competition between the United States and the Soviet Union（前苏联）. Both countries wanted to be the first to send people into space. 

Both the Soviet Union and the United States sent rockets (火箭) into space in the 1950s, but not people. Then in 1961, a man called Yury Gagarin from the Soviet Union became the first man to travel in space. 

People in the United States were upset. They'd hoped an American would be first in space. Soon President John F. Kennedy told the world that Americans would be the first to land on the moon. He said they would get there by 1970. 

Landing on the moon was hardly possible at the time. But that "impossible dream" came true. 

On 16th July 1969, a huge white rocket left the United States. It was carrying a spaceship called Apollo 11. In it were three US astronauts: Neil Armstrong, Michael Collins and Buzz Aldrin. 

Apollo 11 travelled quickly through space. On 20th July, it was near the moon. Armstrong and Aldrin moved slowly into the Eagle. That was their landing craft (登月舱). It would leave the command ship (指令舱) and land on the moon. 

Collins stayed in the command ship. Armstrong and Aldrin watched the moon getting closer and closer. Finally, the Eagle landed. Armstrong used his radio to tell people on the earth, "The Eagle has landed. " He and Aldrin stepped out into (步入) a strange new world. They were walking on the moon!