2. 考研
  3. Our knowledge of the oceans a hundred years ago was confined to the two-dimensional shape of the sea surface and the hazards of

Our knowledge of the oceans a hundred years ago was confined to the two-dimensional shape of the sea surface and the hazards of

admin2020-08-17  4
问题     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 three 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-fathom mark and in the course of a few hundred miles reaches the true ocean floor at 2,500-3,500 fathoms. The slope 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.  
The best title of this passage would be________.
选项 A、Deep Sounding
B、Exploring the Sea Floor
C、Sea Navigation
D、The Continent Slope
答案B
解析 主旨大意题。第一段介绍了人们对海底的认识发展过程，第二段指出如今的海底勘探数据让人们对海底地形有所了解，第三段具体介绍大陆坡。综上可知，本文主要在介绍人们对海底的探索，B项符合文意，故为答案。海水深度、海上航行、大陆坡都是文中提到的内容，但不是文章的中心，故排除A项、C项和D项。
转载请注明原文地址:https://www.kaotiyun.com/show/lfra777K
本试题收录于： 翻译硕士（翻译硕士英语）题库专业硕士分类
0

翻译硕士（翻译硕士英语）

专业硕士

相关试题推荐
随机试题
最新回复(0)