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时间:2016-04-18 20:18:19   作者:周老师   来源:东北师范大学络教育招生   阅读:1212   评论:0
内容摘要:完形填空(Cloze)完形填空1 Why do leaves change color? To the curious mind, this colorful transformation demands an explanation. What determines wheth...


    Why do leaves change color? To the curious mind, this colorful transformation demands an explanation. What determines whether a leaf will turn yellow or red?
    Autumn colors are part of the process by which trees prepare for the winter. The shorter days of autumn alert the tree’s internal clock to begin cutting off the supply of water and nutrients to the leaves. Each leaf responds by constructing a separation layer at the base of the leaf. This layer - composed of a corklike substance- blocks off any circulation from the leaf to the rest of the tree and causes the leaf eventually to fall off the tree.
    While this process is going on, carotenoids (
类胡萝卜素) begin giving leaves their yellow or
orange color. These coloring matters are usually present throughout the summer, but they go unnoticed because of the primary green coloring matter in the leaves. The red color, on the other hand, comes mainly from anthocyanin
(花青素) , a coloring matter that the leaves do not produce until the autumn. During autumn, the green coloring matter breaks up and the yellow and red coloring matters take center stage. When there is no green coloring matter left, some tree leaves turn bright yellow and some others take on a brilliant red color.


    Many businesses, associations, and other organizations maintain a library to Serve the special needs of their workers and members. Such libraries fall into the general category of special libraries.
    The library of a newspaper is a special library. So is the library of a bank, of an advertising agency, or of a company that makes airplanes. The New York Times, for example, maintains a special library for the use of its editors and researchers.
    Special libraries range from tiny rooms to huge buildings. Some spend millions of dollars each year providing library services. The contents of special libraries depend on the needs of the organization they support. In fast-developing fields, special library collections may include few books. These libraries may rely Instead on journals, electronic resources, newspaper clippings, and research or government reports.
    Most special libraries focus on helping their users keep up with rapid developments in a particular field of knowledge. Many of these users are professionals who need up-to-date information to make important decisions.
    Most special libraries have little information on general topics. Therefore, special librarians make extensive use of other sources of information, such as on-line databases, government agencies, research libraries, and university libraries.



Someone has said, “You are never too old for games” So true that is. Age is no barrier to fun and play. Outdoor games take you back to your childhood days. As a child you could hardly keep yourself from hitting the playground, remember? As adults, we become busy in our work routine and fun and play take a backseat. But why not bring out that child in us for a little while! How about playing some fun team games?

Ball games like football, volleyball and soccer are good choices of team games for people, young or old. If you can make arrangements for the sports gear and equipment needed, games like golf or baseball can also be good options for adult team games.
    On looking at these team games for adults, you must have realized that there’s a lot of physical activity involved in most of them, and there’s the small risk of injury or accidents. But falling and standing up again is fun sometimes, isn’t it? So forget all that was bothering you, lock all your worries away, go, be a kid. Play and let play!



Sunshine is a form of radiation. It is what we take for granted on sunny days and miss on cloudy ones. Sunshine has been associated with happiness, joy and smiles. Cloudy days or no sunshine, on the other hand, are associated with problems, sadness and even death. It has been known since the 1920s that death rates in industrialised countries are higher during the winter months, even in warm climates such as Florida or Queensland.
    Medical research has revealed that there are in fact scientific reasons for these commonly   observed phenomena. Sunshine falling on the skin produces vitamin D and this vitamin is now known to protect against heart disease. Sunshine also appears to protect against breast cancer, and again vitamin D is believed to be involved.

There is also evidence that adequate sunshine exposure helps lower blood pressure and that the effect may last up to a week. Sunshine is even a cure for certain types of depression known as “winter blues”.
    Sunshine is free, and a regular dose of a couple of hours a day may be better than an “apple” for keeping the doctor away.

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