Albert Einstein is right once again! He thought of the idea about gravitational waves years ago with his Theory of Relativity, but scientists are finally discovering that it really exists now. But what are gravitational waves, and why are they important?

    Well, gravitational waves are made by black holes and can change time in space. Black holes aren't holes but are lots of matter put together into a very small area. They are created when a star, much like our sun, explodes and leaves behind this dense* material. It doesn't shine like a star any more, and it becomes black.

    The black holes that made these waves are special. About 1.3 billion years ago, there were two black holes that kept moving closer and closer together. Finally, they hit each other and formed one big black hole. The energy is given off and created the ripples* in space. These ripples are gravitational waves. For example, imagine you throw a stone into a pool. It creates ripples that change the shape of the water. Well, that's kind of what the influence of one black hole hitting the other has in space.

    Gravitational waves are hard to explore. But thanks to the efforts of scientists, the ripples were discovered on Feb. 11th, which is the first time in human history. Einstein was excellent to know this 100 years ago before we have the technology. It can give us a new view of the universe we live in. The discovery of gravitational waves, unlike stars, galaxies and other bright objects, black holes don't produce light, so we can't see them by tools. Gravitational waves allow scientists to look at the universe not only with light, but also with gravity. "Everything else in astronomy like the eye," A scientist told The New York Times. "Finally, astronomy grew ears. We had never ears before."

    Now, we will be able to find black holes and things that are much further away from Earth, which means much more space exploration in the future. And who knows, this discovery could even lead to time travel!

Would it surprise you to learn that, like animals, trees can communicate with each other and pass on their wealth to the next generation—their young trees?

    Suzanne Simard, forest ecologist(生态学家) at the University of British Columbia, explains how trees are much more complex(复杂的) than most of us ever imagined. Although Charles Darwin(达尔文) thought that trees are competing for survival of the fittest, Simard and her team have made a new discovery and showed just how wrong he was. In fact, the opposite is true: trees survive through their group work and support, passing around necessary nutrition(营养) such as nitrogen(氮) and carbon "depending on who needs it".

    Nitrogen(氮) and carbon are shared through miles of underground fungi (真菌) networks. This makes sure that all trees in the forest ecological system give and receive just the right amount to keep them all healthy. This system works in a very similar way to the networks of neurons (神经元) in our brains, and when one tree is destroyed, it influences all.

    Simard talks about "Mother trees". These are usually the largest, oldest plants that on which all other trees depend. These "Mother trees" are connected to all the other trees in the forest by this network of fungi, and may manage the resources of the whole trees and plants in the forest. She explains how these trees pass on the wealth to the next generation, transporting important resources to young trees so they may continue to grow. When humans cut down "Mother trees" without paying attention to these highly complex "tree societies" of the networks on which they feed, we are reducing the chances to save the whole forest.

    "We didn't take any notice of it," Simard says sadly. "Mother trees" move nutrition into the young trees before dying, but we never give them chance. If we could put across the message to the forestry industry, we could make a huge difference towards our environmental protection efforts for the future.

The past Chinese diver (跳水运动员) Guo Jingjing appeared at the Paris Olympics this summer, but this time, she was there in a new role - as the chief referee (裁判长). 

Born in 1981, Guo Jingjing started diving at the age of 7. She practiced hard and quickly became very good at it. In 1993, she joined China's national diving team. Guo got hurt many times, but she never gave up. She got the title of world champion (冠军) 31 times in all. She also won 4 Olympic gold medals. 

Guo stopped diving at the age of 30, but she still wanted to do something for China's diving team. She decided to become a referee. After years of hard work, she finally made it. When she appeared at the Paris Olympics, everyone was excited. "I will try my best to make sure that the diving competitions are fair (公平的)" she said. Guo Jingjing would like to help others as long as she has time. She once helped poor children in villages go to school and live a better life. 

In short, Guo Jingjing is a very special person. She sets a great example for young people who want to be divers or just want to work hard at something they love. 

 What does a day look like for a high school student in the United States? Well,I can tell you about my day in high school.

 Our schoolday goes from 8:30 am to 5:30 pm. Sometimes I have cheerleading(啦啦队活动) practice or play practice at 6:30 am. If I have time,I eat breakfast at the school dining room.

 Then I go towards my locker(锁柜) and take my books for the first period. Each class goes for about 50 minutes and we have 10 minutes to get to the next class. We study many things, such as science, maths, French and PE.

I play the piano in a band, so one of my class periods is used for that. Lunchtime is usually at 12:30 pm, and then we have some time to hang out outside or by our lockers. At the end of the day there is a seminar (研讨会) period. It is used for studying or meetings.

 After school, I cheer at a basketball game, or have speech practice. My family always try to have dinner at around 7:00 pm, but there isn't always time. I finally start doing homework at around 8:00 pm or 9:00 pm.

 So there you have it! That's my day in high school.