When Sally was a child, she went to the city park with her mom on a sunny morning. She felt very unhappy. Her mom saw that and asked why. Sally told her mother that she felt so sorry to see so much rubbish on the ground. 

Her mom looked around. There were pieces of paper, boxes, glass bottles and a lot of other rubbish everywhere. "What can we do?" asked Sally sadly." I'm sure you will think of something, "said her mom.

As soon as Sally got home with her mom, she painted a picture of the park and wrote a sign in large black letter at the top of the picture. The sign said, "PLEASE KEEP OUR PARK CLEAN". Later, she took plenty of bags and went back to the park with her mom. Sally put up her picture on a big rubbish box.

The children at the park ran over to see what was going on. Sally handed each of them a bag. "Let's clean up this place," said Sally. Then they began to pick up the rubbish, talking and laughing. Soon, all the bags were full.

Then Sally's mom led them to put the rubbish into different kinds of rubbish boxes. When they looked at the clean park, they all had a strong feeling of satisfaction. 

From then on, Sally has been keeping doing the cleaning and sorting(分类) rubbish. More and more people joined her to play a part in environment protection.