A lot of earthquakes happen in the world every year. Why do earthquakes happen? Scientists tell us the outside of the earth is made of a number of different plates （板块）. The plates move very slowly. Sometimes they stop and don't move for a long time. When some of the earth's plates move suddenly, an earthquake happens.

    Many earthquakes happen under the sea. Sometimes they happen near mountains. In fact, earthquakes may happen anywhere on the earth.

    During an earthquake, the shaking makes rocks rise suddenly and even break openly. Houses fall. People are killed or hurt. Sometimes whole villages or cities are destroyed.

    Scientists have studied earthquakes and made maps that show "earthquake belts". In the areas in these belts, it's possible for earthquakes to happen. In these areas we can make houses strong enough to sand against earthquakes.

    In the future, scientists will be able to predict（预言） exactly when and where an earthquake will happen. They can tell us what to do and how to do as well.

    March 22nd is World Water Day. It started in 1993. It not only makes us think about the importance of water, but also calls on (号召) us to 1 and protect water. Today, we're facing terrible water problems. Among them, wastewater problem is especially2. And the subject of World Water Day in 2017 is “wastewater”.

    What is wastewater? It is used water. Usually, wastewater comes from homes, 3, hospitals and so on. It is produced by different kinds of activities, including washing the machines, taking showers and using the kitchen. The rain also 4 wastewater when it is running down the street during a storm. No matter where it comes from, this kind of water is sure to have5harmful in it.

    6must we treat (处理) wastewater? Wastewater has a big influence on our life. It causes both illness for us and pollution for the environment. We must care for our environment and our own7.

    How can we treat wastewater? Different kinds of wastewater need different ways of treatment. Wastewater 8 homes can be reused. Then there will be 9 wastewater. Also, factory wastewater has to be cleaned 10 it goes back to nature.

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    After a long day's study at school, you are very tired. So after school you go home to relax. When you get home, a robot greets you. He's happy to see you and helps you take your school things to your room. He listens to you talk about your school life and tells you a new joke. And he tells you to call your cousin and to say "Happy birthday". And then he helps you with your homework.

    This is your future, and the robot's name is NAO. NAO has a small body, big eyes and a large head. He can walk and dance. He listens and talks, and he even learns and thinks for himself. His creators (创造者) predict that the robot will be in people's homes before 2040.

    This $16,000 robot knows who you are. NAO can even expressemotions (表达情感). He is a self-guided robot. A self-guided robot can sense (感觉), think and act. Other robots might do two out of the three. For example, a robot might sense things using cameras and think using computers, but with no arms, he can't act. Another robot can move and sense things, but he can't think for himself. These aren't self-guided robots. But NAO can do them all.

    March 22nd is World Water Day. It started in1993. It not only makes us think about the importance of water, but also calls on(号召）us to1and protect water. Today, we're facing terrible water problems. Among them, wastewater problem is especially 2. And the subject of World Water Day in 2017 is "Wastewater".

    What is wastewater? It is used water. Usually, wastewater comes from homes, 3, hospitals and so on. It is produced by different kinds of activities, including washing the clothes, taking showers and using the kitchen. The rain also4 wastewater when it is running down the street during a storm. No matter where it comes from, this kind of water is sure to have5harmful in it.

    6must we treat（处理）wastewater? Wastewater has a big influence on our life. It causes both illness for us and pollution for the environment. We must care for our environment and our own7.

    How can we treat wastewater? Different kinds of wastewater need different ways of treatment. Wastewater8 homes can be reused. Then there will be9 wastewater. Also, factory wastewater has to be cleaned 10 it goes back to nature.

    Nowadays many people are talking about aliens. You might see them 1.

They are very smart, but they look 2. They travel in spaceships.

    But are there really aliens in space? British scientist Stephen Hawking, thinks so. He says that people 3 look for aliens. He thinks they are dangerous.

    On a British TV programme, Hawking says, "It is 4 that there are aliens in space."

    "They might live in big ships. They have 5 all the resources(资源) from their home planet." he says.

    He thinks such aliens might get resources from Earth and then go away. They may bring 6 to the Earth.