When man began to search the skies, he saw a lot of things. In the universe, the earth seemed to be just a small bit of dust. It is only a small planet, and travels around the sun. The sun together with its planets, travels in the Milky Way（银河）, our galaxy（星系）. The Milky way has about thirty billion stars like our sun, and is one of about a hundred million galaxies in the universe. Because the space is so great, it is difficult to work out how far away a star is. Instead of kilometers, we have light years. A light year means the distance light travels in one year. Our nearest neighbour galaxy is more than 9,000,000 light years away from the earth.

    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.

    Can you imagine astronauts' everyday life in space? They also need to eat, 1, exercise and relax. They do the same things as us, but they do 2differently.

    On Earth, we put food on a plate and water in a glass. Gravity（重力）holds the food down and keep the water in the glass.3 there is almost no gravity in space, so food can float（漂浮） away，and astronauts must eat and drink 4.

    Sleeping is very different in space. Some astronauts like to float in the air, but most like to be in a 5bag. They tie（捆绑） the bag to a wall 6they won't float away at night.

    Exercise is very important in space. On Earth, your legs 7 your body, but in space, astronauts float. So they do not use their legs often. This is very 8their legs, they must exercise for thirty minutes every day.

    After a day's work, astronauts relax. They may listen to music, read, watch films, play games, or talk to their friends and families 9 the radio. Sometimes they just enjoy 10in the air.

    As we all know, the environment around us is getting1. In some places we can't see fish swimming in the river or trees on the hills. Some people even have no clean water2.Recently, a new lifestyle called low-carbon life is3every corner of our country. It is such an important project4I can't wait to express my ideas on how to promote (推动) it.

    First, we should5a no-car day every week in our school. Because cars not only cause serious air pollution but also waste energy. On the no-car day, neither students nor teachers6to drive to school. At the same time，just walk or run. Use our bikes and enjoy the fun.

    Second, we had better 7 plastic bags any more. No one can stand the "white pollution", so it is wise to use cloth bags8can be used again and again.

    9, one thing that we should keep in mind is that every big thing comes from small details. So, as students, we should10lights when we leave, use both sides of paper, and reuse our textbooks and so on.

    All in all, just set our mind to these: no-car days, no plastic bags, and no waste. Let's do it now.

    Everyone knows people need water. But do you know just how1water is to living things?

    Maybe you feel lucky2your life isn't hard. But it doesn't mean that you don't have to worry about water. We all face serious water3.

    One of them is water pollution. All kinds of things from cars, factories, farms and homes4our rivers, lakes and oceans dirty. Polluted water is very bad5, people to drink. And dirty water is bad for fish,6. Now, 34 percent of all kinds of fish are dying out.

    How do cars and factories make our water dirty? First, they pollute the air. Then, when it7, the rain water comes down and makes our drinking water dirty. Dirty rain, called acid rain, is also bad for plants, animals and buildings.

    8people have made wells to get clean water. But there still isn't enough. Scientists9that in 30 years, more than half of the people in the world won't have enough clean water.

    When we don't take care of our water, we are hurting everyone. It's time to start learning how to save more water for10and our children.