This is our small world. It is the only one. It is our duty        (protect) it for ourselves and for our children. If each of us        (do) something to help our earth, we will all have a better life. Our air and water        (be) cleaner. It's not too hard to help our earth. We really only need        (try).

    In fact, all of us can        (make) a small change in the way we live. It will make a big difference to our environment. Here are a few tips        (help) save our world.        (not throw) away so much. Pick up litter in the streets. Turn off lights when leaving a room. Turn off televisions and shut down computers when they are not in use.        (bring) your own shopping bag when you go        (shop) . Save water! Take a shower rather than a bath. Turn off the tap while        (clean) your teeth.

    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 us to1and 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 also4wastewater 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. Wastewater8homes can be reused. Then there will be9wastewater. Also, factory wastewater has to be cleaned10it goes back to nature.