Men have always wondered about the earth they live on and about the ①_____ above them.

    When early men looked at the night sky, they asked themselves a lot of questions. They looked at the moon, and wondered what this strange bright object in the sky was. They did not understand why it changed its shape from night to night. They looked at the stars and planets. They also wondered why some of them changed their positions, while others did not.

    ②他们也思考地球的形状。 Most early people believed the earth was flat.

    ③In different parts of the world, there were different ideas about the universe. The ancient Greeks were the first people to study the universe(宇宙) more scientifically. In the sixth century BC Pythagoras put forward the idea that the world was round. However, he could not explain why people at the bottom of the world did not fall off.

    It was not until the sixteenth and seventeenth centuries that scientists found the answers to some important questions. ④With the help of Galileo's telescope, people could see the sky more clearly, and find the positions of the stars and planets. Finally in 1665, Isaac Newton explained to the world what gravity (重力) was and people at last understood why they did not fall off the earth.

    I had a good time on my vacation. I spent my vacation trekking(徒步旅行)in Nepal, a small country in the Himalaya Mountains of Asia.

    On the trekking vacation, I walked for a long time through the mountains. There are very few roads in Nepal, so trekking is the best way to travel. It will be better if you have a guide. The guides know the best paths to take and they can also help trekkers with their bags. Sometimes our guide cooked food for us. Every day, we trekked for about four hours in the morning, and two hours in the afternoon. We slept in the large tents. It was very interesting. I didn't want to go home in the end.

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    Friends are important in our life, because no one wants to be lonely. However, some people have difficulty in making friends and they often feel lonely. {#blank#}2{#/blank#} According to a new study from Chicago University, the reason is that this kind of people have brains（脑）different from common people. And they often feel unsafe when facing strangers.

Does that mean they have no way to become happy again?  {#blank#}3{#/blank#}

    Scientists of this study have thought up ways to help these people deal with their loneliness. They provided four steps for getting out of loneliness.

    The first step is to accept social invitations even if you don't want to go." It's not enough for people just to get in touch with others online. That's because most people don't show their true selves there," said Dr. Cacioppo, one of this study's scientists. {#blank#}4{#/blank#} As" actions speak louder than words", people need to be active to communicate with others. They also need to meet people with the same interests. Also, they should try to expect the best from each activity.  {#blank#}5{#/blank#} Who knows what good things are waiting for us?

    Got a moment -or, maybe, 15seconds? In the age of fragmented(片段化的) time, short, funny videos on smart phones can easily get people interested when they have nothing better to do in their free time. Enter Douyin, which is one of the most popular apps in China; it has over one billion daily plays every day now. Users can make funny short music videos whatever they want.

    Launched(上线)in September 2016, Douyin makes people be able to share their lives with each other, make new friends or just watch funny short videos. Most music videos in Douyin are less than 15 seconds, not only suitable for young people, but for all ages.

    Douyin's international version(国际版), called Tik Tok, is also popular in Japan, where it was in first place on the country's Apple Store free app list for both April and May 2018. After launching in Japan in August 2017, the app now attracts so many young Japanese.

    A report says the country's internet economic(经济) results, in 2017 the market size for short videos was 5.73 billion yuan, while the whole market can reach 35.68 billion yuan in three years.

    It's not surprising that Douyin becomes so successful — all you need to do is picking up your phone and opening the app to make yourself relaxed and have a laugh.

    Jada and Jessie are twins. They were born on August 5. They are ten now and in the fourth grade. Jada and Jessie do everything together. They are in the same class. They dress alike. They look the same. People always get confused (困惑 ). This really makes Jada and Jessie laugh. Teachers always get them mixed up at school. Even their father has trouble telling them apart (分辨). Their mother doesn't, though. She always knows who they really are, Jada and Jessie often try to confuse her, but it

has never happened.

    Their elder brother, Jared, is fifteen. He can't tell the difference between the two sisters. He doesn't even try Jada and Jessie have the same friends. Their friends always mix them up. It doesn't matter to Jada and Jessie.

    One day, their father told their mother to get one of them a different haircut so that he could tell them apart. Jada and Jessie were horrified (恐惧的). They didn't want to look different. They liked looking the same. Their mother came to the rescue ( 拯救), and refused to make them cut their hair. The girls were happy just the way they were and didn't want to change. Their dad just shook his head. He would have to stay confused. Jada and Jessie didn't care. They knew who they were, and that was all that mattered .

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