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).

    Endangered Wild Animals in China

Word Box: endangered 濒危 survivors 幸存者 giant 巨大的 mammal 哺乳动物 alligator 扬子  鳄 mussel 河蚌  reptile 爬行动物 

根据表格所提供的信息选择最佳答案。

    Like most of her friends, Georgie Sanderson has 24-houpa-day access(使用权) to technology through her mobile phone, iPod Touch and home computer. But the 15-year-old girl says she is too busy to spend her days on Facebook. She only uses it once or twice a day. "The 10th grade is busy, and I have to work hard. Even when I'm not studying, I have better things to do with my time, such as being outside or spending time with my friends," she says. Georgie has a part-time job. She watches TV for a while in the afternoon and she helps with the housework.

    Georgie's words prove the findings of a new report. According to the report, teenagers today are not completely dominated(支配) by technology, although they have been into a digital(数字) world. They spend most of their time on their homework, TV, part-time jobs, hobbies, sports, friendship or reading instead of playing or chatting on the computer. But the report also finds that mobile phones are important to teenagers. 95 percent of 18 year-olds have got one mobile phone, and 82 percent sleep with their mobile phones on and beside them all night.

    For Georgie, sleep is more important than texting others. Georgie is also careful about the use of IT. She says, "Social media is helpful, but it is so distracting(使人分心的). I only use it when I do need to use it."

    The best way to teach your children to live a green lifestyle is to live that green lifestyle yourself. When kids see you picking up rubbish from the park, they see value(价值)in keeping public places clean Use these tips to introduce your children to green living：

    Use public transport. Use the car only when necessary; at other times, take trains and buses with your children.

    Ask for their help. Younger children often love grown-up activities. So have them carry a small bag of food waste to the bin, or let them help separate(分开)your recycling. Older children may want to take part in the activities like cleaning up the neighbourhood and organizing the daily recycling If they're not very interested, make environment-friendly activities a family-time priority (优先事项)

    _________________________ Petting farms for younger kids may help prevent(防止)farm animals from becoming something that they see only in books or on television. Many people believe that wild animals shouldn't be kept in any kind of zoos, but they do offer a valuable educational and conservation(保护)lesson. So if you want to visit a zoo, find a zoo that provides its animals with as natural an environment as possible