There are over 37 000 known kinds of spiders（蜘蛛）in different shapes and sizes in the world. The largest spiders live in the rain forests of South America and are known as the "bird-eating" spiders. These spiders can grow up to 28cm long and they eat small birds. The smallest spiders are from Western Samoa. These tiny spiders are less than 0.5mm long. They live in the plants that grow on mountain rocks.

    Some people like to keep spiders as pets but most people don't like touching them. A great number of people are afraid of them mainly because of their poison—something will make them hurt or even die. But in fact, only thirty kinds of spiders are very dangerous to humans. Spiders provide benefits for humans by catching and eating insects such as flies and mosquitoes (蚊子).

    Spiders are different from other animals because they make webs to catch the small insects for food. The special silk of a spider's web is light and strong—five times(倍)stronger than steel. Some people have tried to raise spiders in order to collect their silk but no one was successful in doing it. One reason is that it takes 670 000 spiders to produce half a kilo of silk and all of these spiders need living insects for their food. Besides, spiders are usually solitary (独自的) animals and they need keeping alone.

    All in all people are amazed to learn that there are so many secrets in spiders!

    Some animals sleep during the wintertime because the weather can be very cold and it is difficult for them to find food. They can sleep for a long time. This kind of winter sleep is called “hibernation”.

    If an animal moves about a lot, it needs food. Hibernating animals do not need to eat much because they are not moving about. Their hearts(心脏) beat very slowly and they also breathe(呼吸) slowly. They find a place that is sheltered(遮蔽的) from bad weather and where they are out of danger. Their body fat(脂肪) keeps them alive and warm.

    Some animals, such as bears, may wake up from their hibernation on warm winter days and then quickly go back to sleep again when they see the snow is still thick on the ground. When the weather becomes warmer in spring, the animals start to wake up and look for food.

    No one knows when the first kite was made. The first record of a kite was more than 2,000 years ago in China. Han Xin, the leader of an army, wanted to bring down a king. He decided to dig a tunnel(隧道) into the king's palace. He flew a kite over the wall of the palace to make sure the length(长度) of its string(线). In this way, he could determine how long the tunnel should be. His men in the tunnel took the kite string with them. When they reached the end of the string, they started to dig up.

    Kites have been flown in Japan for hundreds of years. In the 1700s, kites were flown in autumn to give thanks for a good harvest. They were also flown to send good wishes to couples who had their first son. Today in Japan, kites are often flown as part of a celebration, such as the beginning of a new year. And kite festivals are held each year in many parts of the country.

    Kites have been used for scientific purposes in the Western world. In 1752, Benjamin Franklin tied a key to a kite and flew it in a storm to find out that lightening was a form of electricity. In the 1890s, Lawrence Hargrave invented box kites to test ideas about flight. From 1898 until 1933, the United States Weather Bureau (气象局) used box kites to collect weather data. The Wright brothers also experimented (试验) with kites. What they learnt helped them make the first airplane flight in 1903.

    North American black bears are shy animals. They are fearful by nature, and will usually run away if they see or hear people. Because of this, it can be difficult for scientists to learn about these animals.

    In order to study black bears, researchers from New Jersey, the US, catch bears and use drugs to help them go to sleep. Researchers then work out the size and the weight of the bears, take blood, to test for diseases, remove a tooth and take it to the lab to find out its age. From these studies, researchers want to find out how many bears live in New Jersey, how long they live, and how many babies they produce.

    But in Minnesota, the US, researchers study bears that are completely awake. The bears know the researchers' voices and they are not afraid of the research team. With the help of a few grapes to keep the bears busy, researchers can touch them to check their hearts, look at their teeth, and do other jobs. Researchers can also walk or sit with bears for hours and make videos to learn about their everyday lives."

    In both places, the main purpose is the same—to make sure there is a healthy population of black bears. But the research methods and the kinds of information that researchers are able to collect are quite different.

    Thousands of years ago, people didn't know that the Earth moved. They thought the sun really did move across the sky. The Greek god Helios was said to drive the sun across the sky with his chariot (战车). But now, the way people think has changed. Nowadays, it is the sun that drives a "chariot" around the sky.

    What do I mean by this? Well, quite simply, there is now a plane (or "chariot") that is powered by the sun. It has special parts on its wings. These parts absorb (吸收) power from the sun. They absorb so much power that the plane can still fly even at night. In Greek mythology (神话), Helios had to take a break at night. It seems we're finally even more powerful than the gods themselves.

    This plane is called Solar Impulse. It will fly across the US in May. This is very important for the future of the world.

    Why is solar energy (太阳能) important? Well, other kinds of energy are known to cause problems. If you live in China, you've probably noticed the pollution. This is caused by burning coal and gas to make energy. The heat and chemicals created by burning these things give us power. But if we use power from the sun, we don't have to burn anything and there will not be any pollution.

    Solar energy is not entirely ready yet. It needs to be improved. But the best thing about it is that, unlike coal and gas, it doesn't run out. The Solar Impulse plane could pretty much keep flying forever. Of course, the sun's light will eventually run out too one day, but not for another 5 billion years. That's a pretty long flight.

    My name is Peter. I'm from New York and I am in Qingdao with my parents and my sister Lily now. My sister is eleven and I am twelve. We are in the same school. We go to school from Monday to Friday. Our parents are busy working and they don't have time to drive us to school. So we often go to school by bus. Sometimes we also ride a bike to school. We have four classes in the morning and two in the afternoon. My favorite subject is math. Science is my sister's favorite.

    I like sports. I like playing soccer and basketball very much. But I don't have much time to play them on weekdays. I help my sister with her math on Mondays, go shopping with my mother on Wednesdays, and practice Chinese on Friday afternoons. My Chinese friends help me with my Chinese. But on Saturdays and Sundays I can play sports, watch TV and surf the Internet.