新概念英語文章精選

　　隨著《新概念英語》這套教材的引入，已經在全國都引起了轟動乃至學習新概念的潮流。下面是小編帶來的，歡迎閱讀!

　　The Salinity of Ocean Waters

　　海水鹽度

　　If the salinity of ocean waters is analyzed, it is found to vary only slightly from place to place. Nevertheless, some of these small changes are important.

　　如果我們分析海水的鹽度，會發現地區間只有輕微的變化，然而有些小的變化是重要的。

　　There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation -- conversion of liquid water to water vapor. In this manner the salinity is increased, since the salts stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind.

　　導致海洋的鹽度變化的基本過程有三個，其中之一是通過蒸發的方式即把液態水轉化為水蒸氣來減少海洋中的水分。這樣由於鹽留了下來，所以鹽度增大。當然，如果這種方式走向極端，將會餘下白色的鹽晶體。

　　The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean.

　　與蒸發相反的是降水，如降雨，由此水被加入海中，海水被稀釋，從而鹽度降低。這種情形會發生在大量降雨的地區，或江河入海岸處。

　　Thus salinity may be increased by the subtraction of water by evaporation, or decreased by the addition of fresh water by precipitation or runoff.

　　因此，鹽度通過蒸發減少水分而上升或通過降水或徑流增加淡水成分而下降。

　　Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas.

　　一般來說，在陽光很強烈的熱帶地區，海水的鹽度略高於世界上其它沒有熱帶那樣多的蒸發的地區。同理，在江河稀釋海水的海岸地帶，海水鹽度略低於其它海區。

　　A third process by which salinity may be altered is associated with the formation and melting of sea ice. When sea water is frozen, the dissolved materials are left behind. In this manner, sea water directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared.Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water.

　　第三個可以變更鹽度的過程與海洋中冰的形成和融化有關。海水凍結時，溶於其中的物質被留了下來。這樣，在新形成的海水冰面的正下方的海水比在冰形成之前有更高的鹽度。當然，當冰融化的時候，會降低周圍水中的鹽度。

　　In the Weddell Sea Antarctica, the densest water in the oceans is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world.

　　在南極洲邊緣的威德爾海中，結冰過程增加低溫海水的鹽度，從而形成了濃度最大的海水。這些大密度的海水下沉，可以在世界海洋的深水域發現。

　　Cohesion-tension Theory

　　內聚壓力理論

　　Atmospheric pressure can support a column of water up to 10 meters high. But plants can move water much higher; the sequoia tree can pump water to its very top more than 100 meters above the ground.

　　大氣壓能夠支援10米高的水柱，但植物可將水送得更高。美洲紅杉就能把水泵到地面以上100多米高的樹頂。

　　Until the end of the nineteenth century, the movement of water in trees and other tall plants was a mystery. Some botanists hypothesized that the living cells of plants acted as pumps. But many experiments demonstrated that the stems of plants in which all the cells are killed can still move water to appreciable heights. Other explanations for the movement of water in plants have been based on root pressure, a push on the water from the roots at the bottom of the plant. But root pressure is not nearly great enough to push water to the tops of tall trees. Furthermore, the conifers, which are among the tallest trees, have unusually low root pressures.If water is not pumped to the top of a tall tree, and if it is not pushed to the top of a tall tree, then we may ask: how does it get there?

　　直到19世紀末，水在樹木和其它高大植物中的輸送還是一個謎。一些植物學家假定植物中的活細胞充當了水泵的角色。但許多實驗表明細胞都已死亡的植物莖幹仍能將水輸送到相當可觀的高度。對於植物中輸送水的其它解釋都基於根壓——植物底端的根對水的推動。但根壓完全不足以將水推到樹頂。況且，最高樹木中的松柏只有很低的根壓。如果水不是被泵到高樹的樹頂，也不是被推到樹頂，那麼我們會問：它是怎樣到達樹頂的呢?

　　According to the currently accepted cohesion-tension theory, water is pulled there. The pull on a rising column of water in a plant results from the evaporation of water at the top of the plant. As water is lost from the surface of the leaves, a negative pressure, or tension, is created. The evaporated water is replaced by water moving from inside the plant in unbroken columns that extend from the top of a plant to its roots. The same forces that create surface tension in any sample of water are responsible for the maintenance of these unbroken columns of water. When water is confined in tubes of very small bore, the forces of cohesion ***the attraction between water molecules*** are so great that the strength of a column of water compares with the strength of a steel wire of the same diameter. This cohesive strength permits columns of water to be pulled to great heights without being broken.

　　根據目前為人們所接受的內聚壓力的理論，水是被拉到上面去的。一株植物中作用於一個正在升高的水柱之上的拉力來自該植物頂部水的蒸發。由於水從葉子表面喪失，一個負壓力，或張力就得以產生。蒸發出去的水被植物裡流動的水代替。這些水形成水柱從植物頂端一直延伸到根部。在任何水樣中造成表面張力的力支援著這些不斷的水柱。當水被限制在內徑很小的管道中時，內聚壓力***水分子之間的相互吸引力***是如此之大以致一支水柱的強度相當於一根直徑相同的鋼絲的強度。這種內聚壓力使得水柱被拉到非常高的地方而不會斷裂。

　　American black bears

　　美國黑熊

　　American black bears appear in a variety of colors despite their name. In the eastern part of their range, most of these bears have shiny black fur, but in the west they grow brown, red, or even yellow coats. To the north, the black bear is actually gray or white in color. Even in the same litter, both brown and black furred bears may be born.

　　美國黑熊雖然被叫做黑熊但卻有各種各樣的顏色。在它們生活區域的東部，大部分黑熊長有富有光澤的黑毛，但在西部，他們則長著棕色、紅色甚至是黃色的毛。在北部，黑熊其實長著灰色或白色的毛。就是在一胎所生的小熊中，都可能混雜棕毛和黑毛。

　　Black bears are the smallest of all American bears, ranging in length from five to six feet, weighing from three hundred to five hundred pounds. Their eyes and ears are small and their eyesight and hearing are not as good as their sense of smell. Like all bears, the black bear is timid, clumsy, and rarely dangerous, but if attacked, most can climb trees and cover ground at great speeds. When angry or frightened, it is a formidable enemy.

　　黑熊是所有美洲熊中最小的，5-6英尺長，300-500磅重。它們的眼睛和耳朵都很小，他們的視力和聽覺不如嗅覺那樣好。像所有的熊一樣，黑熊膽小，笨拙，很少具有危險性。但如果受到攻擊，大部分黑熊會以很快的速度爬上樹和奔跑。當發怒或受驚嚇時，黑熊會成為可怕的對手。

　　Black bears feed on leaves, herbs, roots, fruit, berries, insects, fish, and even larger animals. One of the most interesting characteristics of bears, including the black bear, is their winter sleep. Unlike squirrels, woodchucks, and many other woodland animals, bears do not actually hibernate. Although the bear does not eat during the winter months, sustaining itself from body fat, its temperature remains almost normal, and it breathes regularly four or five times per minute.

　　黑熊以樹葉、草、樹根、水果、漿果、昆蟲、魚，甚至更大的動物為食。熊類，包括黑熊的最有趣的一個特點是他們的冬眠。與松鼠、旱獺和其它別的林地動物不同，熊並不真正地冬眠。雖然熊在冬天的幾個月中不吃東西，靠體內脂肪維持生命，但它們的體溫保持正常，並有規律地一分鐘呼吸4或5次。

　　Most black bears live alone, except during mating season. They prefer to live in caves, hollow logs, or densethickets. A little of one to four cubs is born in January or February after a gestation period of six to nine months, and they remain with their mother until they are fully grown or about one and a half years old. Black bears can live as long as thirty years in the wild , and even longer in game preserves set aside for them.

　　除交配季節外，大多數黑熊獨自生活。他們喜歡住在洞裡、空心的大木頭裡或茂密的樹叢裡。經過6到9個月的懷孕期後一胎1-4個小熊在1月或2月出生。它們同母熊住在一起，直到它們完全長大，即1歲半左右。黑熊在野外可以活到長達30年，在專門的保護區中甚至能活得更長。