Houses fall down. Trees fall over. Large holes form in the ground. Could Alaska be sinking? That's what some villagers in Alaska have been asking themselves recently and scientists think they know why. Warmer temperatures may be causing Alaska's frozen ground to thaw (解冻).

    About 85 percent of Alaska's land surface has permafrost (永久冻结带). Permafrost supports the ground above it—including trees, houses, and roads. But why is the permafrost thawing?

    Some scientists say that human-caused pollution is leading to global warming. And most scientists agree that Alaska has been getting warmer. They say that the warmer temperature is causing permafrost to thaw in some areas. The thawing permafrost can cause problems for people, plants, and animals.

    The collapsing (倒塌) is a problem in the villages in Alaska which are built on permafrost, and some of them may have to move to safer ground, where there is no permafrost.

    The Alaskan town of Glennallen saw its old post office collapse. And, according to James Walters, a permafrost expert at the University of Northern Iowa, house-moving companies have been very busy.

    “Melting permafrost can also destroy trees and forests,” Walters said. “When holes in the ground form, trees fall into them and die. This could turn a forest into a swamp (沼泽), and animals which need the forests will have to move elsewhere.”

    “The melting could cause severe problems.” Walters says, “This could take hundreds of years, but in the end Alaska will look quite different from what it looks like now.”

Teens For Planet Earth

    This is a social networking site for teenagers who want to get involved in protecting our planet. They can connect with other green-minded teens, choose a project or create their own. Teens For Planet Earth encourages young folks to get busy in their own communities. They offer guidance on local projects with categories such as habitats, animals, water and education. Awards are given to active members.

Meez

    At Meez, teens can create their own avatars(头像), rooms and virtual pets. It is a social community of creative people that combines avatars, virtual worlds and games. Meez offers contests and chat as well as homework help, a fashion central and a writers' corner. A chat area for younger teens is available. Other areas are music, geek（极客）central, art and sports.

Cyberteens

    Cyberteens is another cool site that celebrates the teen years. Here teenagers can find community, games, and news. There is a link called “creativity” where teens can share their poems, stories, photos and artwork. The “cool links” section offers a huge variety of options to the curious teens. This site also has surveys and helps with jobs and school work.

Student.com

    Student.com is a resource site for teens and high school students. Its social network has over 900,000 members. Members earn points to win prizes just by browsing and they offer several multi-player games. Points are used to buy items at auction(拍卖会). Student.com is filled with useful information and articles.

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    It's never easy to explain exactly when a specific language began, and in the case of English we can hardly regard it as a separate language before the Anglo-Saxons came to Britain. Germanic invaders (入侵者) came and settled in Britain from the north-western coastline of continental Europe in the fifth centuries. The invaders all spoke a language that was Germanic (related to Dutch, Frisian, German and the Scandinavian languages), but we'll probably never know how different their speech was from that of their continental neighbors.

    The reason that we know so little about the language in this period is because we do not have much in the way of written records from any of the Germanic languages until several centuries later. When Old English writings began to appear in the seventh and eighth centuries there was a good deal of regional variation (变化), but not more than that found in later periods.

    The Celts already lived in Britain when the Anglo-Saxons arrived, but there are few obvious signs of their language in English today. Some scholars have suggested that the Celtic tongue might have had some influence on the grammatical development of English, particularly in some parts of the country, but this is highly speculative (猜测). The number of borrowed words that have entered Old English from this language is very small. Those that survive in modern English include “comb” (a type of valley), alongside some place names.

    Last week I was riding my special motorbike and then stopped at a convenience store. As I was getting my wheelchair off the back, a man watched me from his car and I noticed a wheelchair in his back seat. We spoke for a moment and I asked him about the wheelchair. He answered that it was for his daughter. "Well, do you think she would like to go for a ride on my motorbike with me?" I asked. He seemed shocked that a total stranger would ask him this. He thought about it for a second and said, "OK, as long as I can follow you."

    He introduced me to Amy and he sat her on my back seat. Her father followed me for a few miles and she talked non-stop about what she wanted for Christmas. As we came back to the convenience store, she said, "This ride is the best Christmas present I could ever receive. I have been in a wheelchair my whole life and didn't know I could do this." I told her about some of the other things I do (ski, travel the world by myself, etc.). As her father was taking her off my bike, she turned to him and said, "Oh Daddy, I'm going to be OK. Mr. Bryant does all kinds of things, and I will too." Her father turned away as a tear of joy rolled down his cheek. He hugged me and said, "I was sitting here praying for a gift for Amy that would encourage her. She often felt that her life was dull compared to other children. God answered my prayer just now. Now I pray that God will bless you for your gift to Amy today." I believed what he said. Being kind and thoughtful to others, we can be an answer to prayer.

    A primary school in Jinhua, Zhejiang Province has announced it no longer requires parents to sign their children's homework, which was aimed at getting parents to supervise(监督) their children after school. China Youth Daily comments: Putting an end to the requirement that parents sign off on the homework of their children eases the burden on many parents, as otherwise they would have to do primary school homework after a hard day's work. But there are worries that if parents stop having to sign off on their children's homework, the children will not get good grades.

    However, the most effective way for children to study is to develop their willingness to learn and do their own studies. When doing homework, students practice and hopefully apply what they have learned. It is true that teachers are supposed to check students' homework and identify their mistakes. But some parents correct their children's mistakes by themselves when signing off on it.

    It is the duty of students to do their homework, be responsible for their studies and correct their mistakes. Parents' supervising their homework, checking their answers and dealing with the harder problems will only make children less aware of their mistakes and encourage them to wait for their parents' help when they face any problems.

    Children have to manage their own learning and develop the ability to study by themselves, as competence will not be achieved if a student simply repeats strict tasks in which he is assisted in school by teachers and at home by parents.

    A delayed satisfaction experiment conducted by Walter Mischel in the 1960s proved that children with better self-discipline(自律) performed better in their studies and interpersonal relationships.

    There is little doubt that parents' supervision can make children's homework better. But it does not give children the chance to practice their ability to solve problems independently.

    Humans and many other mammals have unusually efficient internal temperature regulating systems that automatically maintain stable core body temperatures in cold winters and warm summers. In addition, people have developed cultural patterns and technologies that help them adjust to extremes of temperature and humidity (湿度).

    In very cold climates, there is a constant danger of developing hypothermia, which is a life-threatening drop in core body temperature to below normal levels. The normal temperature for humans is about 37.0℃. However, differences in persons and even the time of day can cause it to be as much as 6℃ higher or lower in healthy individuals. It is also normal for core body temperature to be lower in elderly people. Hypothermia begins to occur when the core body temperature drops to 34.4℃. Below 29.4℃, the body cools more rapidly because its natural temperature regulating system usually fails. The rapid decline in core body temperature is likely to result in death. However, there have been rare cases in which people have been saved after their temperatures had dropped to 13.9-15.6℃. This happened in 1999 to a Swedish woman who was trapped under an ice sheet in freezing water for 80 minutes. She was found unconscious, not breathing, and her heart had stopped beating, yet she was eventually saved despite the fact that her temperature had dropped to 13.7℃.

    In extremely hot climates or as a result of uncontrollable infections, core body temperatures can rise to equally dangerous levels. This is hyperthermia. Life-threatening hyperthermia typically starts in humans when their temperatures rise to 40.6-41.7℃. Only a few days at this extraordinarily high temperature level is likely to result in the worsening of internal organs and death.