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.”

    Before going outside in the morning, many of us check a window thermometer (温度计) for the temperature. This helps us decide what to wear.

    {#blank#}1{#/blank#}. We want our food to be a certain coldness in the refrigerator. We want it a certain hotness in the oven. If we don't feel well, we use a thermometer to see if we have a fever. We keep our rooms a certain warmth in the winter and a certain coolness in the summer.

    Not all the thermometers use the same system to measure temperature. We use a system called the Fahrenheit scale. But most other countries use the Centigrade scale. Both systems use the freezing and boiling points of water as their guide. {#blank#}2{#/blank#}.

    The most common kind of thermometer is made with mercury inside a clear glass tube. As mercury (or any other liquid) becomes hot, it expands. As it gets colder, it contracts. That is why on hot days the mercury line is high in the glass tube. {#blank#}3{#/blank#}.

    First, take a clear glass juice bottle that has a cap; fill the bottle with colored water. Tap a hole in the center of the cap using a hammer and thick nail. Put the cap on the jar. Then stick a plastic straw through the nail hole.

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    Finally, place a white card on the outside of the bottle and behind the straw. Now you can see the water lever easily.

    {#blank#}5{#/blank#}. As the temperature goes down, the water will contract, and the lever in the straw will come down. Perhaps you will want to keep a record of the water lever in the straw each morning for a week.

Sweet Dreams While You Sleep

    Did you sleep the day away on Friday March 21? Well, you should have done that because it was World Sleeping Day.

    This is the day of the year when people around the world care about their sleep and ask themselves questions about sleep.

    Why do we need sleep?

    Nobody as yet can give a perfect answer to this question. However, lab tests on rats have shown that lack (缺少) of sleep over about four weeks leads to a strong drop in body temperature, great weight loss and finally, death.

    How much sleep?

    Different people need different amounts of sleep. Eight hours a night is considered the average amount of sleep. For teenagers, the least number of sleeping hours advised by doctors are 10 hours for primary school students, nine for junior highs and eight for senior highs.

    Some people seem to get along just well with very little sleep at night. Leading American scientist Thomas Edison, for example thought of sleep to be a waste of time. He did, however take naps (打盹) during the day. On the other hand, Albert Einstein, another great scientist, said he needed at least ten hours sleep a night.

    How can we sleep well?

    Here are some of the most popular tips for a good night's sleep:

    Listen to your body clock, not your alarm clock (闹钟).

    Use your bed only to sleep.

    Get up and go to bed at the same time (also on weekends).

    Exercise in the morning and in the early afternoon. Don't exercise in the evening.

    Stop looking at that clock while you can't sleep! And don't worry.

    Avoid alcohol (酒精), caffeine (咖啡因) and smoking before going to bed.

    Keep the bedroom dark, quiet, and cool.

    John Blanchard was studying the crowd making their way through the station. He was looking for the girl whose heart he knew, but whose face he didn't, the girl with the rose.

    When reading a book in a Florida library a year before, John became interested not in the contents of the book, but in the notes penciled in the margin (空白处). The handwriting reflected a thoughtful soul and beautiful mind. He discovered the former owner's name in the front of the book: Miss Hollis Maynell.

    He located her address and wrote a letter introducing himself. The next day he was shipped overseas to serve in the army. During the next year, they grew to know each other through the mail and their friendship developed. John requested a photograph, but she refused, saying if he really cared, it wouldn't matter what she looked like. When the day finally came for him to return home, their first meeting was suggested-7:00 pm at the Grand Central Station in New York.

    She wrote, "You'll recognize me by the red rose I wear on my coat." So now John was in the station to meet the girl with a rose.

    As a pretty and slim girl in green came over, John noticed her blue eyes like flowers in spring. He walked directly towards her, entirely forgetting she was not wearing a rose. As John came closer to her, he saw another woman with a red rose stood nearby. Well past 40, this woman had graying hair done under a worn hat. Seeing the girl in green walk quickly away, John felt as if he were split (劈开) in two. He desired to follow that girl, but longed for the woman whose spirit had truly companioned and supported him.

    The woman looked gentle and sensible. John went to her, saying, "I'm Captain John Blanchard. You must be Miss Maynell. I am glad to meet you here. May I take you to dinner?"

    She replied with a smile, "I don't know what this is about. But the lady in green who just went by, begged me to wear this rose on my coat. She said if you asked me out to dinner, I'd tell you she is waiting for you in the big restaurant across the street. She said it was some kind of test!"

    A student is learning to speak British English. He wonders: Can I communicate with Americans? Can they understand me? Learners of English often ask: What are the differences between British and American English? How important are these differences?

    Certainly, there are some differences between British and American English. There are a few differences in grammar. For example, speakers of British English say "in hospital" and "Have you a pen?" Americans say "in the hospital" and 'Do you have a pen?' Pronunciation is sometimes different. Americans usually sound theirs in words like "bird" and "hurt". Speakers of British English do not sound theirs in these words. There are differences between British and American English in spelling and vocabulary. For example, "colour" and "honour" are British, "color" and "honor" are American.

    These differences in grammar, pronunciation, spelling and vocabulary are not important, however. For the most part, British and American English are the same language.

ZOOKEEPER FOR A DAY

    Go wild with an extreme zookeeping experience!

    The Khaki Extreme program is a wild behind-the-scenes zookeeping adventure like no other! The program offers the chance for 11-15 year olds to see first-hand what's involved in looking after amazing wildlife at Australia Zoo.

    During the guided adventures, you'll gain an understanding and appreciation of what's involved in working in one of the world's most popular zoological and conservation areas, and you'll love getting up close with the awesome animals.

    Whether it's helping keepers prepare diets for the animals, cleaning enclosures (围场) for large animals, or making improved activities for Australia Zoo's wildlife — you will have a chance to get involved at grass-roots level.

    After a busy morning getting up close with wildlife, you can enjoy a specially provided lunch while watching the performance in the world-famous Crocoseum. Then you'll also receive a guided behind-the-scenes tour of the Australia Zoo Wildlife Hospital. Here you'll see the kind veterinary (兽医的) team treating sick and injured native wildlife, and you'll learn what you can do to protect Australia's native wild animals.

    Every season is different and so is our Zookeeper for a Day Khaki Extreme program! We'll change the animals and activities each school holiday period to keep it exciting, but with so many great animals on offer, the Khaki Extreme program is always a bunch of fun.

    If reptiles (爬行动物) are more your thing, check our Zookeeper for a Day Khaki Extreme Reptile program. Here you'll have a wild day out with some of Australia Zoo's most scaly (有鳞屑的) and slippery friends. This program may not be available every school holiday period and program dates will be limited. Check the booking page for further details on availability.

    www.australiazoo.com.au

    Open daily 9:00 am—5:00 pm

    Bedtime for some of our animals is 4:30 pm.

    Closed Christmas Day