There are many kinds of trees. All trees have roots. The roots hold trees in the ground. The roots soak up ( 吸收 ) water and food. Then trees get water and food from the roots. You can't see inside a tree. But you can study how water moves through trees.

    First, get a stalk ( 茎 ) of celery ( 芹菜 ) and cut off its end. Put red colour in a cup of water. Then put the stalk of the celery into the red water. Then we can see the red water moving up in the celery easily.

    After half an hour, take the celery out. Cut it in half. Your celery should be red. This is because the water moved up the stalk. Water moves through trees in the same way as it moved through the celery.

Kunqu Opera (昆曲),also known as Kun Opera, is a kind of Chinese musical drama (戏剧).But it is more than just drama. It is actually a kind of art{#blank#}1{#/blank#}history, music, dancing and others.

It is {#blank#}2{#/blank#}believed that Kunqu Opera is the beginning of all the other forms of Chinese opera. With a long history of over 600 years, Kunqu Opera started in the city of Kunshan at the end of the Yuan Rynasty. It became quite {#blank#}3{#/blank#}in the Ming and Qing dynasties. In 2001,Kunqu Opera was {#blank#}4{#/blank#}as one of the Masterpieces of the Oral and Intangible Heritage of Humanity (人类口述和非物质遗产代表作).

    What makes you who you are as a person? You probably have some ideas of your own personality. Are you similar to Martin Luther King or Albert Einstein? Read about these types and find out.

The weather is getting hotter and hotter. You are thirsty playing basketball or riding home from school. A cold drink may be just the thing. But be careful what you are drinking. Something that looks cool may not be good for your health.

There are plenty of "energy drinks" advertisement on TV. Most of them have beautiful colors and cool names. They tell you they are helpful to your health. Sounds great and lots of people believe them!

But after a careful check you may find that most energy drinks have lots of caffeine (咖啡因) in them. These drinks are especially aimed at young people, students, busy people and sports players. Makers sometimes say their drinks make you better at sports and can keep you awake. But he careful not to drink too much.

Caffeine makes your heart beat fast. Because of this, the International Olympic Committee has limited (限制) its use. Caffeine in most energy drinks is as strong as that in a cup of coffee or tea. Possible health dangers have something to do with energy drinks. Just one box of energy drink can make you nervous, have difficulty sleeping and can even cause heart problems. Scientists say that teenagers should be discouraged from taking drinks with a lot of caffeine in them.

Do you have trouble trying to create the next big idea?

Sometimes the answer isn't to just force an idea out of your mind.

Instead, you might want to try sitting back, relaxing and letting your mind wander（走神）. Yes, you heard that correctly. If you are in need of a new idea, try daydreaming.

Daydreams allow your mind to run freely and even increase productivity in some cases. Daydreaming develops creativity which is why you have an ah-ha moment and sudden insight（领悟） about a situation. Daydreaming allows you to uncover thoughts and ideas you did not realize you even had and get the thoughts hidden under the surface.

Researchers from the University of California, Santa Barbara, found a connection between daydreaming and creative problem-solving. Their study includes making participants first do an "unusual-use task". They had to try to come up with as many different ways to use an object as they could.

Then, the participants choose to do one of the following four things before doing the "unusual-use task" again; complete a difficult task, complete an easy task, take a 12-minute break, or skip a 12-minute break and move right on to the task exercise again.

Surprisingly, the group that performed best was the one that completed the easy task. Many participants reported that they were daydreaming while performing the easy task. So the researchers believed that this daydreaming might have helped unlock their creativity.

But how could daydreaming help the brain come up with creative ways? The answer is something known as "unconscious thought". Even when you are not actively working to solve a problem, it is still in the back of your mind. Your brain is still thinking about the problem, but in a way that you are unaware of.

When you daydream, your mind is allowed to think in ways it normally would not. Because it is free of control, it can create completely new and out-of-the-box ideas.

Great ideas never come easily, but that does not mean you always have to work hard to get them. Feel free to do what you want and let your mind wander.

①Franz Schubert was a music giant (巨匠). He wrote several symphonies (交响乐) and operas, about600 songs, and had many other musical works.

②Schubert was born in a musical family in Vienna on January 31, 1797. His father was a teacher, and he taught young Schubert to play the violin. One of Schubert's brothers also gave him piano lessons. Schubert was really good at writing all kinds of music. Schubert started working at his father's school in1814, but he didn't like teaching. So he spent most of his free time writing music. During that time, he wrote his first full symphony and opera. He also wrote many famous songs.

③In 1818, Schubert gave up teaching to make music full time. It was a good change. People liked his music, and they even paid him to write music for them. Schubert finally made money from his musical works, but they didn't make him rich.

④Schubert died at the age of 31 on November 19, 1828. Schubert and his music were popular during his time. And people still listen to his music today.