【课文】 First listen and then answer the following question. 听录音，然后回答以下问题。 How did people probably imagine the sea-floor before it was investigated? Our knowledge of the oceans a hundred years ago was confined to the two-dimensional shape of the sea surface and the hazards of navigation presented by the irregularities in depth of the shallow water close to the land. The open sea was deep and mysterious, and anyone who gave more than a passing thought to the bottom confines of the oceans probably assumed that the sea bed was flat. Sir James Clark Ross had obtained a sounding of over 2,400 fathoms in 1839, but it was not until 1869, when H.M.S. Porcupine was put at the disposal of the Royal Society for several cruises, that a series of deep soundings was obtained in the Atlantic and the first samples were collected by dredging the bottom. Shortly after this the famous H. M. S. Challenger expedition established the study of the sea-floor as a subject worthy of the most qualified physicists and geologists. A burst of activity associated with the laying of submarine cables soon confirmed the challenger"s observation that many parts of the ocean were two to there miles deep, and the existence of underwater features of considerable magnitude. Today, enough soundings are available to enable a relief map of the Atlantic to be drawn and we know something of the great variety of the sea bed"s topography. Since the sea covers the greater part of the earth"s surface, it is quite reasonable to regard the sea floor as the basic form of the crust of the earth, with, superimposed upon it, the continents, together with the islands and other features of the oceans. The continents form rugged tablelands which stand nearly three miles above the floor of the open ocean. From the shore line, out a distance which may be anywhere from a few miles to a few hundred miles, runs the gentle slope of the continental shelf, geologically part of the continents. The real dividing line between continents and oceans occurs at the foot of a steeper slope. This continental slope usually starts at a place somewhere near the 100-fatheom mark and in the course of a few hundred miles reaches the true ocean floor at 2,500-3,500 fathoms. The slope averages about 1 in 30. but contains steep, probably vertical, cliffs, and gentle sediment-covered terraces, and near its lower reaches there is a long tailing-off which is almost certainly the result of material transported out to deep water after being eroded from the continental masses. T.F.GASKELL Exploring the Sea-floor from Science Survey 【New words and expressions 生词和短语】 navigation n. 航海 sounding n. 水深度 fathom n. 寻(1寻等于1.8米) porcupine n. 箭猪 dredge v. 挖掘 expedition n. 远征 physicist n. 物理学家 magnitude n. 很多 topography n. 地形 crust n. 地壳 rugged adj.崎岖不平 tableland n. 高地 sediment n. 沉淀物 terrace n. 阶地 erode v. 侵蚀 【课文注释】 1.be confined to 限制在，局限于 例句：He was confined to bed for a week with his cold. 他由于感冒而被限制在床上躺一个星期。 The work will not be confined to the Glasgow area. 此项工作不会局限于格拉斯哥地区。 2.hazard ①n. 危险，冒险，危害 例句：The car had its hazard warning lights on. 这辆汽车亮起了危险信号灯。 ②v. 冒险，赌运气 例句：He hazarded all his money in the attempt to save the business. 他为挽救这家企业，不惜冒险投入他的全部金钱。 I"ll hazard a dollar on the bingo game. 我在这局宾果游戏上赌一元钱。 【词义辨析】 danger, risk, hazard, menace, peril, threat 这些名词均含有“危险、威胁”之意。 danger: 含义广，普通用词，指能够造成伤害、损害或不利的任何情况。 risk: 指有可能发生的危险，尤指主动进行某种活动或去碰运气而冒的危险。 hazard: 比risk正式，多指偶然发生的或无法控制的危险，常含较严重或有一定风险的意味。 menace: 所指的危险性最严重，表示使用暴力或造成破坏性的可能。 peril: 指迫在眉睫很有可能发生的严重危险。 threat: 普通用词，语气弱于menace，指任何公开侵犯对方的言行，给对方构成危险或威胁。 venture, chance, dare, hazard, risk 这些动词均含有“敢于冒险”之意。 venture: 指冒风险试一试，或指有礼貌的反抗或反对。 chance: 指碰运气、冒风险试试。 dare: 可与venture换用，但语气较强，着重挑战或违抗。 hazard: 主要指冒险作出某个选择，隐含碰运气意味。 risk: 指不顾个人安危去干某事，侧重主动承担风险。 3.irregularity n. 不规则性，不规则的事物 例句：Adjust this setting to control the amount of irregularity in the wind. 调节设置控制风的不规则的数量。 4.shallow water 浅水区 5.open sea 无边际的大海 6.gave more than a passing thought 稍微想过 7.H. M. S. 是Her/His Majesty"s Ship (英国皇家海军舰艇)的缩写。 8.at the disposal of 交由……支配 dispose v. 清除，处理掉，解决，杀死，打败 例句：His job is to dispose of the rubbish every night. 他的工作是每晚清除垃圾。 Hardship disposes man to meet adversity. 艰苦能让人适应逆境。 He doesn"t know how to dispose of his spare time. 他不知道怎样安排业余时间。 disposal n. 处理， 处置， 布置 例句：We placed everything at his disposal. 我们把一切事情都交给他处理。 He has a large number of reference books at his disposal. 他有大量的参考书可供使用。 9.dredge v. 用挖泥机疏浚 例句：Can we dredge the river to make it deeper? 我们能不能把这条河疏浚得深一点? 10.a relief map 地形图 11.with, superimposed upon it, the continents, together with the islands and other features of the oceans 这是with引导的一个过去分词独立主格结构。因逻辑主语太长，所以使用了倒装语序。superimposed upon it 是逻辑谓语部分。 12.rugged adj. 高低不平的，崎岖的，粗糙的 例句：They walk on the rugged country road. 他们在崎岖不平的乡村小路上走着。 The path to glory is always rugged. 通向光荣的道路常常是崎岖的。 13.continental shelf 大陆架 14.1 in 30 1/30 15.erode vt. 腐蚀， 侵蚀 例句：Soft drinks erode your stomach lining. 软饮会腐蚀你的胃壁。 The sea have erode the cliff face over the years. 海水经年累月冲刷著峭壁的表面。 【参考译文】 本世纪已研制出许多新奇的交通工具，其中最新奇的要数气垫船了。1953年，有一位50多岁名叫克里斯托弗.科克雷的原电子工程师，改行在诺福克郡的湖泊地区从事造船业，他向英国政府和工业界提出了他研究多年的一项计划。他的设想是：用一个低压空气或软垫来支撑船体，软垫周围用高压空气环绕。自那以后，人们很难决定是否应该将这种运载工具列为轮船、飞机，或是陆上交通工具，因为它是介于船和飞机之间。作为一个船舶技师，科克雷尔在寻找解决波浪阻力的方法，因为波浪阻力浪费掉了船在水面行驶的大量动力，从而限制了船的速度。他的解决办法是把船体提离水面，让船在一个气垫上行驶，气垫只有一两英尺厚。船底装上大量环状喷气嘴以实现这一目的。这样，船就能飞了，但飞不高。它的飞行限决于它所悬浮的水面或地面。 1959年，在苏伦特海峡进行的首次试航引起了轰动，气垫船先是在水面上行驶，后又登上海岸，爬上沙丘，最后停在路上。后来气垫船跨越英吉利海峡，平衡地在波浪上方行驶，波浪不再产生阻力。 从那以后，各种各样的气垫船出现了，并开始了定期航行服务。气垫船在非洲、澳大利亚等交通不发达地区特别有用。它能成为“飞行水果盘子”，把香蕉从种植园运到港口。大型的气垫班轮或许能跨越大西洋。未来的火车或许能成为“气垫火车”，靠气垫在单轨上行驶而不接触轨道，时速可达每小时300英里。气垫船的前途是不可限量的。
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