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.

    We may learn from the news that the world is hungry. Many people in poor areas don't have enough food to eat. In fact, our world is also 1. We are still short of water though water 2 nearly 3/4 of the Earth. About 97% of water on the Earth is seawater and we can't drink it or use it to water plants 3 . People can only drink anti use the 3% of the water from rivers and lakes. What's worse, we can't use all of that because of water 4 .

    Now we are facing a serious problem-we need more water. First, we need to learn how to save water. Then we need to 5 ways to reuse water. Scientists have made a lot of studies. The 6 show that in many large cities and small villages, people 7 use water only once and then it runs to the sea or rivers. So we can reuse water. Last but not least, we should make full use of the seawater. Scientists are trying to solve the 8 —collecting clean water from seawater 9 we can do now is to save water and not to waste water. We cannot live long 10 enough clean water. So let's work together to do something.

    Have you heard of STEM education? STEM 1 Science, Technology, Engineering and Mathematics. It means students can learn these 2subjects in one class. And they work on many projects to practice 3 they learn STEM education is very 4 in the US.

    Now more than 600 5 middle schools bring in STEM education, according to the paper, en. Beijing, Yuying School is one of them.

    The school 6 the course in May. It invited college teachers to teach more than 80 students programming, robotics and other interdisciplinary(跨学科}的) knowledge.

    The teaching style is quite 7, Once teachers finish teaching basie knowledge, studentes will practice it 8. For example, after learning about electrie circuits(电路),students are required to design one that could control three lights 9.They have many projects to improve their hands-on 10 as well. Once, they had a "smart home" model design project. All the students competed to design a 11 model and make it "smart" .Liu Tianyou, 12, with 12 teammates, used computer programs and sensors to finish it. "If you open the door of the house, the lights will 13 automatically, "he said. Their work won the third prize.

    The class, develops students' creativity as well. 14 Learning mechanies and programming in the class, Zhao Hngyi, 14, made a Lego robot himself in eight 15.From assembling(组装)to testing he finished it on his own. The robot can catch things and walk on certain tracks under orders. " It's cool to make my idea come to life," he said.

    When talking about inventors, who do you first think of? Forget Thomas Edison. Meet the teenage 1 at the 24th Jiangsu Adolescents Science &. Technology Innovation Contest(江苏青少年科技创新大赛).

    Wang Xingyu, from Kunshan No. 2 Middle School, invented "a 2 line" in the zebra crossing. Wang often saw people running through

the red 3 , so he thought of an idea,

    "I 4 a spray tube(喷管) in the zebra crossing. When the light is red and 5 crosses, it sprays water. If the light is 6, it will not work," said Wang.

    But does it 7 water? "There's a water channel(槽) on the ground, so the water will be collected and 8 again," he said. Zong Hangchen, from Nantong Special Education Middle School, also got his invention idea from daily experience.

    Zong's 9 could only feel a little light. When he walked on the sidewalk for the blind, he often came across obstacles(障碍物). Once he 10 hurt his nose.

    11 help himself and the blind, Zong made something that has radar(雷达) and a loudspeaker. Users tie radar onto their knees and 12 the loudspeaker around their necks. When they meet obstacles, the radar will see them and the loudspeaker will make a 13 to tell the users.

    Chen Huijuan, an official from Jiangsu Association for Science and Technology, was 14 at these inventions.

    15 some ideas are simple, the creations are very good," she said. "Get inspiration( 灵感) from small things in life and you can be an, inventor, too.

    Tigers are strong and dangerous. But now, the big animal is calling for our1.

    There were once eight kinds of2in the world, 3three died out during last century. In the last 70 years, the number of Siberian tigers(东北虎) has gone from as many as 300 to somewhere 418 and 22.

    WWF started a programme recently(最近) to put an end(停止) to tiger poaching(非法狩猎) and 5wild tigers. China, together with 12 other countries, has joined in.

    The Siberian tiger is already6of the world's most endangered(濒危的) animals. If the government doesn't take any action, it's quite7that there will be no more Siberian tigers in China in 10 to 20 years. Animals such as deer, sheep and wild boars(野猪) are the tigers' main food. There isn't enough8for wild tigers because of the hunting of these animals. So the 9 thing people can do is save the animals which tigers eat." To protect the tigers, we need to call on more people to 10 eating and hunting wild animals."