Canals are watercourses constructed to improve and extend natural waterways

游客2024-10-31 24

问题    Canals are watercourses constructed to improve and extend natural waterways. They are generally built to facilitate transportation, but from the beginning they have been used for many additional purposes including draining swamps, irrigating land for cultivation, and promoting economic development.
   Canals are often classified by the size of vessel they can accommodate. Some small local canals, which are able to float only 100 to 300 ton boats or small rafts of timber, may be only 3 feet deep. Major barge canals generally range from 6 to 9 feet in depth, and some are as much as 10 or 12 feet deep. These canals can carry 1,350 to 2,000 ton craft. Ship canals are 25 feet or more deep and are capable of accommodating large vessels in the seagoing class.
   Canals may also be classified as either water level or lock canals. Water level canals do not vary in height along their courses. The best known of these is the Suez Canal, which is at sea level. Lock canals, which include most modem waterways, contain locks, or special devices for raising and lowering boats along their courses by changing the depth of the water. Each lock is a stretch of water enclosed by gates at each end. After a boat enters the lock, water is let or drained out until it reaches approximately the same level as the water ahead. [br] The second paragraph makes it clear that______.

选项 A、the Arthur story reflects a historical transition in human civilization
B、Arthur story is legendary and has no real life basis
C、Arthur story is greatly exaggerated and unbelievable
D、Arthur story reflects people’ s good expectations of their leaders

答案 A

解析选项A的意思为：“亚瑟的故事反映了人类文明史上的一个历史转变。”第二段指出，从石头中拔出剑这个故事反映的是石器时代向青铜器时代的转变。青铜器的使用进一步解放了生产力，解放了人，因此，掌握了青铜提炼技术的人理所当然地成为具有神力的人，成为文化英雄(culture hero)。(注：青铜时代是石器时代后、铁器时代前的一个时代。)B意为：“亚瑟的故事是传奇，没有真实基础。”C意为：“亚瑟的故事被大大地夸大了，因此不可信。”D意为：”亚瑟的故事反映了人们对其领袖的良好期望。”

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