Coloring is an activity that children worldwide have long enjoyed. With a picture already made for them, kids simply chose a crayon, pencil or marker of their favorite color and fill it in. Today, it also becomes more and more popular among teenagers and even adults, who are enjoying relaxing hours of coloring. In December, five of the top ten best-selling books in the United States were coloring books.

    They are fun, but are coloring books good for you?

    The good feedback(反馈)from customers is encouraging. Trina Lucida, a popular artist creating coloring books, says that many of her customers are buying the coloring books for others who are sick or going through a hard time. She adds that the "big idea" behind her latest book is to encourage people to do something creative.

    Lucida is right, according to Allan Rohan, a psychology(心理学)professor. "Many customers think of coloring books as a new creative stage," he said in an interview, "but what's more important is that people spend time coloring in order to reduce stress after a long day." Research shows that coloring can reduce stress by guiding people to focus on(专注)one simple task. When a person is filling in a flower with a light purple color, he focuses on the flower and forgets about all his troubles in life.

    Experts add that coloring may relieve a certain kind of pain. Doing the coloring helps people relax their mind and calm down. Also, coloring helps people's brain in a healthy way. The shape of the drawing makes one side of the brain active, while the color of the drawing improves the other. Coloring can bring out your imagination and take you back to your childhood. Interesting, isn't it?

    "It's very relaxing," said Susan Jackson, a big fan of Lucida's coloring books. "Coloring frees my mind. And it's not just to try to fill blank(空白的)pages. The pictures make me happy and there is just something about them. So I'm saving the pictures I like best to the very end."

    Most of us spend a third of our lives sleeping. Scientists have been studying the brain to learn what happens while we sleep. Scientists tell us that there are four stages(阶段)of sleep. During each stage our brain behaves differently, and so does our body. Each stage is marked by changes in the pattern of brain waves, which can be recorded by machines.

    In the first stage, we drift off to sleep. Our muscles(肌肉)begin to relax. Our heartbeat and breathing slow down. Body temperature and blood pressure(压力)begin to drop. Stage-two sleep is a time of small, fast brain waves. Our eyes move quickly from side to side as if watching a movie. This is known as rapid eye movement, or REM sleep. During REM sleep, dreaming takes place. In stage three the brain wave becomes slower again.

    Within about 45 minutes after falling sleep, we progress into the fourth stage – deep sleep. As this happens, our brain sends out slower but larger brain waves. This is the most restful kind of sleep, but it is also the time when sleepers are most likely to change positions or sleepwalk. After deep sleep we return to stage two. As the hours pass, we repeat the sleep cycle four or five times. Then we wake up.

Laughter is natural for people. We start to laugh at about four months of age, We start to laugh even before we start to speak. 

Laughter connects us with others. We laugh more when we are with other people, It's difficult to pretend to laugh. Laughter is honest. {#blank#}1{#/blank#} When do people laugh? 

Only 10 to 20 percent of laughter is about something funny. Most laughter is about being friendly with other people. Most laughter says, "I don't want to compete with you. I want to be friendly with you." This kind of laughter brings people together. 

{#blank#}2{#/blank#} In movies, there is often a joke at an exciting moment when everyone feels nervous. It is usually a small joke, but we laugh a lot. Our laughter helps us relax. 

{#blank#}3{#/blank#} Not everyone has the same sense of humour. Some people think a joke is funny, but other people don't think so. {#blank#}4{#/blank#}

Our idea of what is funny changes with time, For young children, the world is new, They are interested in many things, so they laugh a lot. Teenagers often laugh to protect themselves. {#blank#}5{#/blank#} They laugh at things that give them stress, too. Our reasons for laughter change gradually.

It happens every spring. Flowers come out everywhere on the same day. But how do plants "know" when to flower?

For years, it has been a difficult question for scientists. But a US research group may have finally answered it—the secret lies in a protein(蛋白质)called FKF1. This helps plants to know when the days become long and when they get short. Then they can tell the seasons(季节)are changing.

Researchers found the FKF1 protein when they were studying a plant called Arabidopsis. It is sensitive(敏感的)to sunlight, and can be made active by sunlight.

Plants produce this protein every day in the late afternoon all year. If there is no light at this time, for example, in winter when the sun goes down early, the protein won't be active. But when spring comes and the days get longer, the FKF1 protein can be made active by day light and the plants "know" it is time to flower. " If there is light in the late afternoon, plants will know that the days are getting longer and that it is the best time for flowers to come out,"explained Takato Imaizumi, leader of study. But when conditions are poor for growing, such as during autumn or winter when the weather is cold and days are short, plants won' t flower.

Although researchers have only studied how the FKF1 protein works in the Arabidopsis, they believe that it is the same with many other plants, including crops such as rice and wheat.

"If we can control when flowers come out, we might be able to increase crop production," Imaizumi said.

China's Tiangong space station can help scientists study space. It is also a place for astronauts to live and work. How much do you know about the lives of astronauts working in the space station?

For astronauts in space, exercise is important. The environment is very different in space. Doing sports helps astronauts stay healthy. How do they exercise? There are good exercise machines in the space station. They make it easy for astronauts to keep healthy. 

There is no gravity, so astronauts can't take showers like us. Is there a bathroom in the space station? How do they keep themselves clean? Tiangong has a special bathroom. Astronaut s can clean themselves with a wet towel (毛巾). 

What do astronauts eat in the space station? There is bread and milk for breakfast. There are also tasty Chinese dishes, like Kung Pao Chicken, fried rice and fried noodles. There is a special "fridge" to store (储存) food. The food stays cool in it. 

What if astronauts miss their families? There is special communication equipment (交流设备) in the space station. Astronauts can have private (私人的)"sky- to- earth" calls with their families. The astronauts often wear a headset (耳机). It not only helps them talk with each other, but also makes it possible for them to talk to the ground from any place. 

My parents and I take a trip to the mountain on the Double Ninth Festival（重阳节）each year. We always g{#blank#}1{#/blank#} up very early in the morning. The weather is usually cool at this time of year, so we always spend our whole day there. As we walk t{#blank#}2{#/blank#} the forest, the wind b{#blank#}3{#/blank#} gently on our faces. The mountain roads are c{#blank#}4{#/blank#} by dry yellow leaves. Everything is so beautiful! We always have p{#blank#}5{#/blank#} at the top of the mountain.