Can dolphins talk? Maybe they can't talk with words, but they talk with sounds. They show their feelings with sounds.

    Dolphins travel in a group. We call a group of fish“a school(一群)。” They don't study, but they travel together. Dolphins are mammals(哺乳动物)，not fish, but they swim together like fish in a school.

    Dolphins talk to the other dolphins in the school. They give information. They tell when they are happy or sad or afraid. They say” welcome” when a dolphin comes back to the school. They talk when they play.

    They make a few sounds above water. They make many more sounds under water. People cannot hear these sounds because they are very, very high. Scientists make tapes of the sounds and study them.

    Sometimes people catch a dolphin for a large aquarium(水族馆). People can watch the dolphins in a show. Dolphins don't like to be away from their school in an aquarium. They are sad and lonely.

    There are many stories about dolphins. They help people. Sometimes they save somebody's life. Dolphins' meat is good, but people don't like to kill them. They say that dolphins bring good luck. Many people believe this.

    The sun, the moon and the stars are all in the sky. We see the moon and the stars at night. The sun is a ball. It's much bigger than the moon. It gives us heat (热量). The sun has a family. It's the biggest member of the family. The moon is a ball, too, like the sun and the earth. Sometimes it looks as round as a plate (盘子). Sometimes it looks half a plate. It looks bigger because it's much nearer to the earth. It's much smaller than the sun. It's smaller than the stars. The light (光) on the moon comes from the sun. It has no light of its own.

    The stars look smaller than the sun. They look small because they are very far away from us. All day the stars are in the sky. But the light from the sun is too bright. We can't see the stars in the day.

    What was discovered by accident? The answer is penicillin (青霉素). It kills germs. By killing germs, it saves lives. Suppose you are sick. You go to a doctor. She examines you. She says you have a “staph” infection (葡萄球菌感染). She gives you some medicine. You take it. The medicine knocks out the staph. Soon you are well. Before penicillin, this would not happen. Staph was almost sure death.

    Everyone wanted a medicine. Laboratories worked day and night. They grew the staph in small dishes. Then they tried to kill it. Nothing worked.

    The laboratory dishes had covers on them. They kept things from falling into dishes. Molds (霉菌) were a big worry. They are always in the air. You can't see them. They're too small. There are thousands of different molds. Molds can make an experiment (实验) fail. That's why dishes are covered.

    Dr. Alexander Fleming was working to kill the staph germ. He worked for years. One day he took a cover off a dish. He looked inside. There was a thick growth of staph germ. There was also some mold. Then he saw something strange. Where the mold was, there was no growth of staph. This is what Fleming probably thought. “By accident, I found a mold to kill the dreaded staph.”

    This is how penicillin was found. But here's the real miracle (奇迹). There are thousands of kinds of molds. But only one kind can kill staph. The mold must have fallen into the dish a few days before. The cover was probably off only a few seconds (秒). In those few seconds the right mold fell into the right dish. Another man might have thrown the dish away. But Fleming was very careful and smart. He understood what the mold did. How lucky the humans were!

We can enjoy a one-day weekend every week. Maybe one day is too short, but we can try to plan the time well. {#blank#}1{#/blank#}

★Get up early. The weekend is not only a time to sleep in. {#blank#}2{#/blank#} That's too bad. You can have more free time if you get up early. 

★{#blank#}3{#/blank#} We have to spend much time on our homework. You can feel better if you do your homework early. You can get up early and do your homework first.And then you can have free time to play well. I often do my homework in the morning. So I don't have to worry about（担心）it in the rest of the time.

★Go out for fun. Think about what you like to do. {#blank#}4{#/blank#} You can also visit a museum, a zoo or a park.

A. Here are some ideas.

B. Do the homework early.

C. Some of us get up for lunch!

D. We worry about the homework.

E. Plan a sports activity like playing football in the park.

① After a relaxing weekend, children have to go back to school on Mondays. For parents, they should do something helpful to let their children get to school on time. 

② Let children take a good shower. It's good for children to take a shower before they go to bed. It can not only help them sleep well but also save time next morning. 

③ Ask children to go to bed early. School usually starts at 8 : 00 a. m. So please let your children go to bed before 9 : 30 p. m. Your children should sleep for about nine hours every day. This is quite important as they have to get up early next day. 

④ Make a good breakfast for children. Breakfast can help children study better in the day. It can help students listen to teachers carefully and think well in class. Also, it's good for their health. 

⑤ Getting to school on time is very important for your children. So please try your best to help them. If you can do the things above, they will study and live happily.