We often read the Air Quality Index （空气质量指标） or AQI reported in the newspaper. The AQI helps us understand what the air quality around us means to our health. The AQI uses colors, numbers and words to tell us about the air. Let's see what these colors and numbers mean.

    When the weather is hot, you go to a lake or an ocean. When you are near a lake or an ocean, you feel cool. Why? The sun makes the earth hot, but it can not make the water hot. Though the air over the earth becomes hot, the air over the water stays cool. The hot air over the earth goes up, then the cool air over the water moves in and takes the place of the hot air. When you are near a lake or an ocean, you feel the cool air when it moves in. You feel the wind and the wind makes you cool.

    Of course, scientists cannot answer all of our questions. If we ask "Why is the ocean full of salt?" scientists will say that the salt comes from rocks. When a rock gets very hot or very cool, it cracks (崩裂), and rain falls into the cracks. The rain then carries the salt into the earth and the rivers. The rivers carry the salt into the ocean. But then we ask "What happens to the salt in the ocean? The ocean does not get saltier every year." scientists are not sure about the answer to the question.

    We know a lot about our world. But there are still many answers that we do not have, and we are curious(好奇的).

    What might the future be like? Here are some predictions(预测): things to come, things to go.

    The Spring Festival has caused headaches for millions of Chinese. More than 2 billion people travel at the same time and the journey is difficult. But in 28 years, Spring Festival travel may not be a problem at all. China plans to build more than 120,000 kilometers of railway and a fast transportation network that will serve 90% of the population by 2020. And because most of China will be cities, people will not have to go to other places to find a job, so it will no longer be a problem.

    Newspaper will come to an end in 2043. In the future, digital(数字的) newspapers will be sent to personal web tools through Internet. Readers can discuss topics with journalists and editors. Information will move faster.

    Oil is running out faster than expected. But scientists have found something else for oil as fuel(燃料). Coal, natural gas, nuclear power(核能) and even water can take the place of oil as sources of energy(能源).

    Schools will go electronic(电子化). Computers will be important and popular among the students. Everything will be in the computer and students will not need to bring books to school. They will find information on the Internet. A computer will be the students' library, schoolbag and connection to the outside world. There will be robot teachers, they will check homework on computers and communicate with the students' parents through e-mail. And school buses will be comfortable and safe.

Jason and his parents moved from a small, quiet town to a big city. They moved because Jason's mother was starting a new job there. His father was an artist. He could do his job at home or anywhere else. At the end of June when school was over, the large moving van (搬家汽车) arrived. Jason said goodbye to his friends. They all promised to stay in touch.

At first, Jason was scared of the city. It was noisy and crowded. It made him nervous. They lived in a apartment building now, and Jason missed their old house and yard. However, after a while, he met a boy named Nick who lived in his building. Jason and Nick went to the park together. They flied kites are played ball with other kids.

By the time school began in the fall, Jason liked his new neighborhood. He had learned that go friends and neighbors make it easy to live anywhere!

On the stage of America's Got Talent, 11-year-old Tyler Butler Figueroa played the violin well. Also, he touched many people's hearts {#blank#}1{#/blank#} his story. Tyler comes from North Carolina {#blank#}2{#/blank#} he was four years old, he had a health problem and started to lose hair. He felt sad. The feeling got even {#blank#}3{#/blank#} when his classmates laughed at his look. And they stayed away from him. One day, Tyler saw a flyer (小传单) for free after-school violin lessons at school. He knew he was not {#blank#}4{#/blank#} in music, but he decided to learn to play the violin. "I practiced {#blank#}5{#/blank#} in my room every day," he said. "{#blank#}6{#/blank#} the violin could help me to forget the bad things." Tyler's mother said the violin made him {#blank#}7{#/blank#} again and she felt like she had her son back. Tyler stood strong, {#blank#}8{#/blank#} he had to face those bad things. He {#blank#}9{#/blank#} a book. He wanted to share his story with other kids like {#blank#}10{#/blank#} and told them to be strong.

In Africa there is a beautiful river. A little crocodile(鳄鱼) called Mamba lives here with her 1 . Every day, Mamba hunts(捕猎) fish and frogs for food. How 2 she lives!

One day, she is swimming down the river and see a bird. She goes after it and tries to hunt it. "Don't do that, Mamba!" says Mum and Dad Crocodile. "That is the crocodile bird. He can help 3 our teeth. Now open your mouth. "

4 when the bird flies in, Mamba closes her mouth quickly! "Mamba! Open your mouth now. " Mum Crocodile is very angry. Mamba opens her mouth and the crocodile bird flies 5 as fast as it could(尽可能快地). "I don't want clean teeth, " says Mamba, "and I just want to eat something. "

Then one day Mamba's teeth hurt(疼痛) a lot and she can't 6 anything. A monkey advises her to clean them with a stick(棍子). She tries but still feels 7 in her teeth. 

"Oooooh!"She opens her mouth wide and cries, "Can someone help me?"

At this time, the crocodile bird flies down from the tree, and flies in Mamba's mouth. He runs all over 8 teeth and gives them a good clean. "Thank you so much, " says Mamba, "Now I know 9 you are called the crocodile bird. "

From that day on, they start to help each other and become good 10 .