Now many people like to keep dogs as their pets. But how did dogs become humans' close friends?

    In some places of Europe (欧洲), about 10,000 years ago, some wild (野生的) dogs often came to human's houses to find food. The wild dogs looked different from the ones today. They looked like wolves (狼). At first, they felt ① frightened. They always stood and looked for a short time. Then they got the food and ran away. Sometimes the young dogs couldn't run fast and people caught them. People trained them and the young dogs grew up with the help of people. Slowly, the wild dogs became home dogs. They could make home safe when people were away. They helped people hunt (狩猎). They helped people keep warm on cold nights. ② Sometimes, they could smell and hear danger before people could. In some cold places, they helped people pull (拉) things people need.

    Now there are more than 400 different kinds of dogs in the world. And they look different from each other. The number and kind are growing all the time. Today, some people mainly (主要地) regard dogs as pets. In fact, dogs are really our close friends. We should protect them from being killed.

    Eleven countries are building a great wall of trees across Africa. It is called the Great Green Wall. The aim is to bring life to the dry lands and help to fight the bad environment.

    The wall is 8, 000 kilometers long and 15 kilometers wide. It covers from Senegal in the west to Djibouti in the east, on the south of the Sahara Desert (撒哈拉沙漠). So far, Senegal has made the best progress by planting about 11,000,000 trees.

    Many years ago, there were few trees in that area and the winds used to be very strong. It was harmful to the fields. Also, there was little rain, so few plants could grow and many people went hungry. Since the tree planting project started, the trees have provided food for the local people and increased the wetness (湿度) of the air. Little by little, there appeared green fields for people to grow plant.

    The project which began in 2007 is supposed to cost a total of 8, 000, 000, 000 dollars. Many countries are trying their best to help to continue the planting. So we will be able to see the whole green wall across Africa in the near future!

Information Card

    Good study habits are important for all students. When you have good study habits, you will learn faster and find you have a good memory.

    Do you usually study in the living room？This is not a good place for study because it's really too noisy. You need to study in a quiet place, such as your bedroom. A quiet place will help you learn better.

    Before you begin to study, do not forget to clean your desk. It helps you study well, too. Light is important, too. You will feel tired easily if there is not enough light.

    Of all the good study habits you can develop, asking questions is the key. Just ask. No one knows everything, but we can always learn from each other by asking questions.

    When do you work best？Are you an early bird, a night owl (猫头鹰), or something in between ?Find your most productive work time, and then plan to study at this time.

It was Saturday. After dinner, Mary would like to see a film with her 1 . But her mother said, "Could you please do the dishes, Mary? I have to go to 2 your brother."

Mary's brother Mike was ill in3 . Her father worked in another town and he was very

4 and couldn't come back. Mary had to help her mother do some chores. But her mother usually did everything and Mary didn't know 5 to do it.

Mary decided to 6 her friend a call first. On the phone, she told her friend to wait for her at home. Then Mary's mother7 her how to do the dishes. Before 8 , Mary's mother said, "Be9 , Mary. Don't drop them."

"Don't 10 , Mommy," said Mary. "They're light. I don't think they'll hurt my feet."