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.

    The World Health Organization(世界卫生组织) says air pollution kills seven million people around the world each year. Even if polluted air does not kill us, it can make us very sick.

    However, breathing dirty air may do more than hurt your body. It can also affect(影响) your brain and your ability to think.

A new study shows that air pollution can cause a "huge" reduction(减少)in our intelligence(智商).The researchers reported that long-term exposure(暴露) to air pollution can affect a person's mental(智力的) abilities in two areas: language and math.

Xi Chen, the researcher of the Yale School of Public Health led the study. He and his team found that breathing polluted air can reduce a person's education level by about one year.

    Chen said that the effect(结果) generally is worse for those over 64 years of age, for men and for those with little or no education.

    "The older persons-they are more affected. And we find, quite interestingly, men are more affected than women. And people working outdoors are more affected than people working indoors.

The researchers noted that the effect of pollution on language ability is even more serious as people age, especially among men and the less educated.

    Why were language skills more affected than math? There are two main kinds of tissue(组织)in the brain: white matter and grey matter. White matter is more connected with a person's language skills, while grey matter is connected to our ability to solve math problems. Studies have shown that air pollution has a great effect on the white matter in the brain, but not the grey matter.

    Chen said that air pollution did affect the math skills, just not as much as their language skills.

    Earthquakes are hard to predict, but do you know what to do before, during and after an earthquake? Here's some advice:

    Before an earthquake. It's necessary to prepare yourself and your family. All family members should know how to turn off the gas, water and electricity and know useful telephone numbers (120, 110, 119, etc.). Never put heavy things over beds.

    During an earthquake. It's important for each of you to stay calm. If you are indoors, quickly move to a safe place in the room such as under a strong table. The purpose(目的) is to protect yourself from objects. Stay away from windows, large mirrors, heavy furniture and so on. If you're cooking, turn off the gas. If you're outdoors, move to an open area like a playground. Move away from buildings, bridges and trees. If you are driving, stop the car as soon as possible and stay away from bridges and tall buildings.

Stay in your car.

    After an earthquake. Once the shaking has stopped, DO NOT run out of the building at once. It's better to wait and leave when it's safe. Check around you and help the people who are in trouble. If your building is badly broken, leave it. If you smell the gas, get everyone outside and open windows and doors. If you can do it safely, turn off the gas. Report it to the gas company.

Why Do People Blink (眨眼) Their Eyes?

    People blink their eyes tens of thousands of times every day. Scientists have long believed blinking was an involuntary movement and served mainly to keep the eyeballs wet. But a new study suggests it has a more important purpose.

    An international team of scientists from the University of California at Berkeley studied the blinking of human eyelids. The journal Current Biology published their findings. The team said they found that blinking "repositions our eyeballs so we can stay focused" on what we are seeing. They said that when we blink our eyelids, the eyes roll back into their sockets—the bony area that surrounds and protects the eyes. However, the researchers found the eyes don't always return to the same position (位置). They said this causes the brain to tell the eye muscles (肌肉) to reorganize our eyesight.

    Gerrit Maus is the lead writer of the report. He serves as an assistant professor of psychology at Nanyang Technological University in Singapore. Maus said, "Our eye muscles are quite sluggish (迟缓的) and imprecise (不精确的), so the brain needs to constantly adapt (改编) its motor signals to make sure our eyes are pointing where they should be. Our findings suggested that the brain measures the difference in what we see before and after a blink, and orders the eye muscles to make the needed corrections." The researchers said that without such corrections our surroundings would appear unclear and even jumpy. They said the movement acts "like a steadicam (摄影稳定器) of the mind."

    The researchers said they asked volunteers to sit in a dark room while storing at a small dot on a flat surface. They used special cameras to follow the volunteer's blinks and eye movements. After each blink, the dot was moved one centimeter to the right. The volunteers did not notice this, but the brain did. It followed the movement and directed the eye muscles to refocus on the dot. After the dot was moved in this way 30 times, the volunteers' eyes changed their focus to the place where they predicted it would be.

    Professor Maus said. "Even though the volunteers did not consciously register that the dot had moved, their brains did, and adjusted (调整)with the corrective eye movements. These findings add to our understanding of how the brain constantly adapts to (适应) changes directing our eye muscles to correct for errors in our bodies' own hardware."

No matter what you want to do with your life, you'll need an education first. You make your own future. You want to be a doctor, a teacher, or a police officer? A good education is required for every single one of those careers (职业). And what you're learning in school today will decide whether your country can meet the greatest challenge in the future. 

The truth is, being successful is hard. Some of the most successful people in the world are the ones who've had the most failures. For example, the first book of J.K. Rowling, the writer of Harry Potter, was refused 12 times before it was finally published (出版). Michael Jordan was once kicked off his high school basketball team. He lost hundreds of games and thousands of shots during his career. But he said, "I have ailed over and over again in my life. But that's why I succeed." These people succeeded because they understood that the failures were the mother of their success. So if you get a bad grade, that doesn't mean you're stupid. In fact, you need to spend more time studying. 

I expect you to put your best effort into everything you do. So don't let us down, don't let your family or country down. Most importantly, don't let yourself down.