new students.

    The world itself is becoming much smaller by using modern traffic and modern communication. Life today is much easier than it was hundreds of years ago, but it has brought new problems. One of the biggest problems is pollution. To pollute means to make things dirty. Pollution comes in many ways. We see it, smell it, drink it and even eat it.

    Man has been polluting the earth. The more people, the more pollution. Air pollution is still the most serious. It's bad for all living things in the world, but it is not the only one kind of pollution. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us angry more easily.

    Many countries are making rules to fight pollution. They stop people from burning coal in houses and factories in the city, and from putting dirty smoke into the air. Pollution by SO₂ is now the most dangerous kind of air pollutions. It is caused by heavy traffic. We are sure that if there are fewer people driving, there will be less air pollution.

He found the place difficulty.

    Last year, I worked in a middle school near my mother's house, and I stayed with her for a month. During that time, I helped her do some housework and buy some food.

    After the first week, I noticed that the food was eaten up very quickly. Then I began keeping an eye on my mum. To my surprise, I found that she would put some of the food into a paper bag and go out with it at about nine every morning. And finally, I decided to follow her. I saw her taking the food to the street children. She would also spend a lot of time talking and playing with them.

    One day, I talked to a neighbour and found out that my mum was well-known in the area. The children were very friendly with her and even thought of her as their own mother. Then it hit me-why wouldn't she want to tell me about it? Was she worried that I would stop buying food if I found out?

    When my mum got home, gave her big hug(拥抱)I told her she didn't need to keep it a secret from me. And she told me something about the children. Some of them lived with an old lady in a small house. Others slept on the street. For years, she was helping the poor street children by giving them food. After she told me everything, I was so moved by how selfless(无私的)she was. She helped others in need. As her son, was so proud of my mum.

    I continued to buy food for my mum after that. But I always added one more bag for her other children.

— Yes. They tried to run away, but ________ the police caught them.