【正文】 ckness by making a glacial advance downvalley. A series of negative years may cause a glacial retreat, meaning that the terminus is melting faster than the ice is moving downvalley. Glaciers have been likened to mighty rivers of ice. Although they move many times more slowly, glaciers have equivalent changes in flow rate and often form falls of fastmoving ice above slowmoving ice pools. Glaciers flow faster down their centers than at ice margins, and more quickly at the surface than at the bed. ... How fast a glacier moves is mostly dependent on the thickness of the ice, and on the angle of its surface slope. Glacier speeds vary when changes are made in this geometry. They respond to excessively high seasonal snow accumulations by generating bulges of thicker ice that may move downvalley many times faster than the glacier39。支原體沒有細胞壁，故細胞柔軟，形成分枝狀的細胞，故稱支原體。細菌的細胞壁由肽聚糖組成，十分堅固。細菌將永遠生活在我們身邊。真菌與植物的主要區(qū)別在 于 :真菌貯藏的養(yǎng)料是肝糖 ,而綠色植物主要是淀粉。它的大小用納米（ nm )表示。大多數(shù)病毒是由核酸和蛋白質組成的。 侵入和脫殼：病毒粒子被宿主細胞通過吞噬作用給“吞進”了細胞。 3year rotation of wheat and shum and of lying fallow。s exciting to us is the application of this highpressure chemistry to understanding the outer plas, Jeanloz said. As more plas are found in unexpected orbits around other stars, the effects of internal chemical processes will need to be further clarified in order to obtain a general understanding of pla formation and evolution, the authors concluded in the Science paper. Our solar system39。70s were responsible for recurrences of dust storms in the region. 補充：由于 dust bowl 導致的洛杉磯地區(qū)的移民增加 In the 1930s and 1940s, the region also received two waves of major migrations: that of farm families from the southern Great Plains migrating west to escape the Dust Bowl, and that of African Americans moving out of the American South. During World War II (19391945) the need for labor, especially in ship and aircraft production, boosted the population even more. The population of Los Angeles County jumped from 3 million to million between 1940 and 1950. 托福聽力背景知識 (十 ) 天上掉鉆石 Is It Raining Diamonds On Uranus？ Berkeley October 1, 1999 If experiments at the University of California, Berkeley, are any indication, future explorers of our solar system may well find diamonds hailing down through the atmospheres of Neptune and Uranus. These plas contain a high proportion of methane, which UC Berkeley researchers have now shown can turn into diamond at the high temperatures and pressures found inside these plas. Once these diamonds form, they fall like raindrops or hailstones toward the center of the pla, said Laura Robin Benedetti, a graduate student in physics at UC Berkeley. The team, led by Benedetti and Raymond Jeanloz, professor of geology and geophysics, produced these conditions inside a diamond anvil cell, squeezing liquid methane to several hundred thousand times atmospheric pressure. When they focused a laser beam on the pressurized liquid, heating it to some 5,000 degrees Fahrenheit, diamond dust appeared. They report their experimental findings in a paper in the Oct. 1 issue of Science. The demonstration that methane can convert to diamond as well as other plex hydrocarbons in the interiors of giant plas like Neptune hint at a plex chemistry inside gaseous plas and even brown dwarf stars. Brown dwarfs are small, dim stars barely larger than the largest gas giant plas. This is opening the door to study of the interesting types of chemical reactions taking place inside plas and brown dwarfs, Jeanloz said. Now that technology is able to reproduce the high pressures and temperatures found there, we are getting much better quality information on the chemical reactions taking place under these conditions. It is not amazing that chemistry like this happens inside plas, it39。當?shù)竭_一定的數(shù)量以后，會組成新的病毒粒子。它不能單獨進行繁殖，必須在活細胞內才能繁殖。由此可見病毒是多么微小。但總的來說 ,真菌對 人類還是大有益處的。 真菌與細菌的主要區(qū)別在于 :真菌是真核生物 ,而細菌是原核生物。還有厭氧細菌；好氧細菌和兼性細菌。細菌微小，大多數(shù)只有 微米，但少數(shù)卻有 毫米，如納米比亞硫磺珍珠細菌。分布廣泛，繁殖快且類型多樣。 they are found on all the continents except Australia and they span the globe from high altitudes in equatorial regions to the polar ice caps. There is a delicate balance between climatic factors that allows snow to remain beyond its season. Scientists and skiers alike can note that within a few days of falling, snowflakes have noticeably begun to change. ... The snowflakes are pressed under the weight of the overlying snowpack. Individual crystal near the melting point have slick liquid edges allowing them to glide along other crystal planes and to readjust the space between them. Where the crystals touch they bond together, squeezing the air between them to the surface or into bubbles. During summer we might see the crystal metamorphosis occur more rapidly because of water percolation between the crystals. By summer39。 地外行星看起來通常是完整的，或近乎完整的。 外層行星：木星，土星，天王星，海王星和冥王星。 冥王星。所以，我們可以毫不費力地觀察到黑洞背面的星空，就像黑洞不存在一樣，這就是黑洞的隱身術。我們都知道，光是沿直線傳播 的。 質量小一些的恒星主要演化成白矮星，質量比較大的恒星則有可能形成中子星。到這時，恒星就變成了黑洞。七十年代中國精神病發(fā)病率是 ?，現(xiàn)在上升到 ?，大約一千五百萬人。貓得了舞蹈病，也就是水俁病，這時人還可以進行及時的救治。汞中毒有一定的征兆性，開始是走路不穩(wěn)，面容癡呆，爾后耳聾眼瞎，重者全身麻痹，最后精神失常，以至死亡。人體受汞慢性中毒的臨床表現(xiàn)，主要是神經性癥狀，有頭痛、頭暈、肢體麻木和疼痛、肌肉震顫、運動失調等。二 甲基汞在酸性條件可以分解為甲基汞。水中汞的本底濃度，內陸地下水為，海水為 一 2ppb，泉水可達 80ppb 以上，湖水、河水一般不超過 。施里曼創(chuàng)造性的發(fā)掘所取得的輝煌成就，使他成為了現(xiàn)代考古學的開拓者。盡管家喻戶曉的“荷馬史詩”描述了希臘史前的故事，但學者們認為，盲詩人荷馬的史詩，最初是許多民間行吟歌手的集體口頭創(chuàng)作，因而不能當作歷史，只能視為神話傳說。 奧德修斯回到自己的國家后，雅典娜女神把他變成 一個流浪漢，在一個養(yǎng)豬人家同兒子特勒馬卡斯見面。由于糧食耗盡，幾個同伴趁奧德修斯睡著之際偷殺了太陽神養(yǎng)的神牛。除歐呂卡洛斯外，大家都進入宮殿，并痛快地大吃乳酪、糖蜜、大麥和葡萄酒摻雜魔法藥草的飲料，結果大伙都變成了豬。風神送給他們一只風袋，西風送他們一行往東平安地通過西西里島和意大利半島之間的墨西拿海峽駛入愛奧尼亞海。 希臘聯(lián)軍在特洛伊城內大肆屠殺和掠奪后，回國途中觸怒了天神。 最后，足智多謀的奧德修斯獻出了“木馬計”，米阿加米農所采納。雙方分別為帕特洛克拉和赫克托舉行了隆重的葬禮，并約定雙方休戰(zhàn) 12 天。這個時候，戰(zhàn)爭已僵持不下，而希臘聯(lián)軍內部也發(fā)生了矛盾。帕里斯禁不住看了她兩眼，頓時動心。當 3 位女神見到帕里斯后