职称英语理工类AB级阅读理解经典练习题(5)

　　The Compass 　　Two thousand years ago the Chinese had already developed a working compass. A piece of lodestone would be cut into the shape of a ladle . Placed on a stone board with a smooth surface, the lodestone would move round until the handle of the ladle pointed south while the bulk of the ladle was attracted to magnetic north. This interestingly shaped device is mentioned in a book from about A.D. 80. Other ancient books may have dated it as far back as the fourth century B.C. Jade finders played an important role in the invention of the ladle. They travelled great distances to look for jade. In order not to lose directions, they would take a ladle with them. 　　However, the making of a ladle was a tough job. Much work needed to shape a piece of lodestone into a ladle would mean much of its natural magnetism had been lost. This again meant that only a few ladles could have been produced. Small numbers of ladles produced and growing need for navigation led to a search for ways to produce more compasses, and at the same time, smaller and better compasses. 　　A Columbus was a great sailor and discoverer. 　　C The invention of the compass is important in human history.