A seabird named Lydia recently made a 26-day nonstop(不间断的)journey of about 2,500 mi­les, just to search for food for her baby. She is fitted with a satellite tracking device (卫星跟踪仪). Her trip started on Oct. 18 from Christmas Island in the Indian Ocean. The trip is known as the lon­gest nonstop journey by one of these endangered seabirds.

      Before that, this kind of birds was known only to fly a few hundred miles from where they live, staying away for just a few days at a time. They usually fly over the sea.

      The scientists feel it strange that Lydia made such a long, nonstop journey and flew overland. So the above facts raise some serious questions about efforts to stop the decline(减少)of the birds. The number of the birds has fallen by 10 percent over the past 20 years.

Besides, the scientists are surprised that she was away from her baby for such a long time. They wonder why she needed to go that far. Maybe it shows that fish resources (资源)around Christmas Island are not large enough now. That might explain the slow decline of the bird 一 sea pollution(污染) is serious.

      Our sun is a star, and nine worlds (天体) move round it. Worlds like these are planets. But here are other stars, other suns, not only thousands of them, but millions of them. Do different stars have planets? We can see the planets round our own sun. But we haven't been anymore. The stars are too far away from us. Stars give out light, but the planets don't have any light of their own. So we can't see them. They are too far, and too dark. Still, we can tell that some stars have planets. While a big planet goes round, it pulls its star to one side. And sometimes we can see this. Then we know that the star has a planet. For example, Barnard's Star is a small red star. And it is the quickest star in the universe. But sometimes it moves slower, and then quicker again. We have known Bernard''s Star for many years, and now we are sure it has a planet.

Have you ever experienced the feeling of falling as you start to fall asleep? Sometimes you may come to realize this feeling. If so, don't worry. Many people have felt the same thing.

In fact, these muscle twitches (肌肉抽搐) in the arms, legs or other parts of the body are called hypnic jerks (入睡抽动) or sleep starts. And they are very common. Up to 70 percent of people experience them sometimes, Huffington Post reported. But what causes it?

There are some theories(理论). Some scientists believe that the feeling of falling comes from the body relaxing itself, especially if the person is anxious or unable to get comfortable. As you're about to sleep, your muscles become relaxed. But your brain stays awake. It misunderstands the relaxing of your muscles as a sign that you're falling. Then the brain jerks the body awake as if it's trying to protect you.

    Other scientists believe that different phases of sleep might cause the hypnic jerks. When we sleep, we experience two phases: non-rapid eye movement (NREM) and rapid eye movement (REM). During REM, our heart rate (心率), breathing and nervous system can act irregularly (不规律地). If the body experiences flashes (一瞬间) of REM while entering sleep, these irregularities could cause twitches.

If you don't want to experience hypnic jerks, scientists have some suggestions. When you become deeply relaxed, you can learn how to reconnect slowly by moving your fingers and toes a little bit. Then start to move your head and open your eyes, while being aware of yourself as you get out of the relaxed state.

    But experts agree that hypnic jerks, though sometimes scary, are harmless. If it wakes you up, simply roll over and go back to sleep. But keep in mind: a caffeinated (含咖啡因的) drink, exciting evening activities or stress may make hypnic jerks happen more often.

Where does the wind come from? What makes the wind move(移动) all the time? Scientists tell us that it is the sun. That makes air move, and makes it blow(吹). When the sun shines on the earth, it makes the earth hot. Then the earth makes the air hot. When the air becomes hotter, it also becomes lighter(更轻). The light air goes up. Cool air comes into take the place of（代替） the hot air. The hot light air goes up higher and higher until it becomes cool. Then it comes down again, and then the earth makes it hot again, and it has to go up. When the air move, it has wind.

    How do you keep cool during summer? Air conditioners or electric fans are good 1 in modern society. But 2 that, people could only use fans.

    Over 3,000 years ago, fans began to 3 They were made of feathers (羽毛), bamboo or silk. They came in different 4 , including round and square.

    Later, with the invention of paper, folding(可折叠) paper fans became popular5 the Song Dynasty.  There are usually beautiful 6on fans. Some are landscapes (风景). Others are flowers and animals. Moreover, many great people including Su Dongpo, a poet of the Song Dynasty, and Tang Yin, a scholar (学者) and painter of the Ming Dynasty, once painted their masterpieces(杰作) on fans. This made fans not only 7 tools in daily life but also great artworks.

    So, with its value of beauty, people take fans as a 8 of status(地位). That's why in old China, emperors and scholars often held fans.

    Today, fans are also great collectors' items(藏品) and gifts. On the opening ceremony of the 2008 Beijing Olympic Games, folding fans were9 to leaders and officials (官员) of other countries. While they were 10 fans to get cool, they were also experiencing Chinese culture.