Have you ever asked your relatives or friends if there is Wi-Fi in their houses? Have you ever searched for Wi-Fi when you are at restaurants or hotels? The answers will probably be "Yes". Most of us want Wi-Fi everywhere as if we can't live without it. But we can only use free Wi-Fi in some public places. We still have to spend some money accessing(连接)the Internet at most time. Here comes a piece of good news.

    A rich, powerful organization(组织) in the USA called the Media Development Investment Fund (MDIF) has decided to change the age of online computing (计算) completely by giving free Wi-Fi to every person on Earth. They will send up hundreds of satellites into low Earth orbit(轨道).

    This is because they have made a survey(调查) and found that only 60% of the world's population have been able to get information on the Internet. And this is also because many countries are unable to offer people the necessary infrastructure(基础设施)to access the web.

    We can hope to use free Wi-Fi everywhere in the near future.

阅读以上信息，用恰当的词完成下面的表格，每空一词。

    Mayme Clayton collected books， magazines and letters written by African Americans. Her son， Avery Clayton， thought her collection was important. Unlike most books， these were rare and hard to find. They were written by writers who helped shape African American culture.

    One book in the collection was written by Phillis Wheatley. Wheatley was a slave who wrote poetry. She was the first African American to publish a book. Wheatley herself signed (签名) the book in the Claytons' collection. No one else owns a copy signed by Phillis Wheatley.

    By the time she passed away at age 83， Mrs. Clayton had more than 30，000 books by or about black people. Her collection also includes papers about slaves， photographs， movies， sheet music， and personal letters by black leaders and artists. It is one of the biggest personal collections of African American history and culture in the United States.

    Avery Clayton's dream was to create a museum for his mother's treasures.  Scholars say that Mrs. Clayton's collection is very important. Without her work， part of African American heritage (遗产) would have been lost. “We didn't know these things existed，” says Sara Hadron of California's Huntington Library.

    The collections new home is likely to be in Culver City， California. Part of Avery Clayton's dream is to share the cultural riches his mother collected with others. He especially wants children to have a chance to see the collection. “ At present African American culture is being explained by pop culture，” he says， “ It's important to offer a more complete picture.”

    Cars are very important in the life of the Americans. ⑴Without a car, most American people would feel that they are poor. And even if a person is poor, he doesn't really feel poor when he has a car. ⑵Henry Ford was the man who started making cars in large numbers. He probably didn't know how much cars would affect the American culture. Cars have made the United States a nation on wheels. And ⑶it has helped to make the United States what it is today.

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    The population of Earth is still going up. There will be less and less good land for growing crops in the future. People worry that there will not be enough food for everyone in the middle of this century.

    Recently scientists have discovered one strange plant named fedtschenkoi（玉吊钟）may help. It can absorb（吸收）carbon dioxide(CO₂) at night. It only needs 10 times less water than food plants like beans. This means it can grow in the desert(沙漠).

    In which ways could this plant help us?

    Since deserts are increasing in size because of the changes in Earth's climate, growing plants there will be more and more important. Although it is dangerous to eat this plant, scientists can still study something about it: how it absorbs CO₂ at night while many other plants only do this during the day, and why it is suited to the desert.

    There is another direction to take the research in. Producing a desert plant to eat will be difficult, but there is still possibility to use the genes(基因)from this plant and put them into food plants.

    The other way is to grow this type of plant for fuel(燃料). At the moment we grow plants for fuel in good land. If we do it in deserts instead, more good land can be used to grow plants for food.

    Desert plants have special qualities, which could be an answer to our future food or energy needs. Scientists are working hard on it.

    A bottle of water may not seem much to you, but thousands of bottles will be of great help for people who live in drought-hit areas in China.

    Since last autumn, there has been very little rain in Southwest China. Some places, especially in Yunnan, Guangxi, Sichuan and Guizhou, have experienced a serious drought. Crops died, the land cracked(裂开) and wells and rivers died up. More than 20 million people are having difficulty finding safe drinking water.

    After learning about the drought, many people around the country helped by giving water, money and other things.

    The serious drought has also made students realize the importance of saving water. Students from Nanshan Middle School in Huizhou, Guangdong, went on to the street to tell people to take part in water-saving activities.

    "I've heard that some children in drought-hit areas don't have enough drinking water. I feel really sad about that," said one student. "I decided to take a shower twice a week instead of every day to save water." He said.

    Teeth are important part of our body. Everyone should brush his or her teeth every day. Learning how to take care of teeth is very important.

    The importance of brushing teeth

    If you eat and do not brush your teeth, pieces of food that stick to your teeth can cause problems. The food can damage (破坏)your teeth. Then germs (细菌)can get into your teeth and make them decay (腐烂).

    It is important to brush teeth every day. You should get a checkup from your dentist every year. Trying not to eat food that has a lot of sugar, such as candy and soft drinks, helps to protect teeth.

    The proper ways of brushing teeth

    Do you know that most people do not brush their teeth in the right way? Follow the methods below and they will help you keep your teeth healthy, clean and beautiful.

    ◆Replace your toothbrush every few months.

    ◆Clean two or three teeth at a time. Brush the front of your teeth with a circular motion (运动)and clean the backs of your teeth with up and down motions.

    ◆Use a gentle back and forth motion to clean the tops of your teeth where you bite (咬)into food.

    ◆Don't forget to gently brush the top of your tongue (舌头)from back to front. A lot of germs live there.

    ◆Take at least 2 minutes to brush your teeth.