Passage One
A rapid means of long-distance transportation became a necessity for the United States as settlement(新拓居地) spread over farther westward. The early trains were impractical curiosities, and for a long time the railroad companies met with troublesome mechanical problems. The most serious ones were the construction of rails able to bear the toad, and the development of a safe, effective stopping system. Once these were solved, the railroad was established as the best means of land transportation. By 1860 there’ were thousands of. miles of railroads crossing the eastern mountain ranges and reaching westward to the Mississippi. There were also regional southern and western lines.
The high point in railroad building came with the construction of the first transcontinental sys tem. In 1862 congress authorized two western railroad companies to build lines from Nebraska west ward and from California eastward to a meeting point, so as to complete a t
A. brought about a rapid growth of industry and farming in the west
B. attracted many visitors to the construction sites
C. attracted labourers from Europe
D. encouraged people to travel all over the country
| There is a great deal of controversy within the
medical profession regarding the use and value of the coronary bypass procedure,
and for more than eight years the American Heart Association has discussed the
question at its regular scientific sessions. The bypass operation consists of open heart surgery in which the physician takes a vein from the patient’s leg and implants it near the heart to construct a passage around the blockage in a clogged artery so that blood can flow freely by. The operation performed on about 100,000 persons a year in the US and costs approximately $10,000. The procedure is designed to relieve tie pain of angina pectoris which occurs when the blood supply’s obstructed and also to allow the patient more freedom of sustained activity. In persons with advanced heart disease and blockage in severa A. is a better way of prolonging one’s life B. is the only solution to the blockage of one artery C. should be used to prevent advanced diseases D. has no effect at all on serious patients [判断题]加强接点有极继电器，当衔铁与铁芯极靴之间的间隙最小时（即吸起状态）的位置为定位，与动接点闭合的接点叫定位接点。
A.正确 B.错误 我来回答: 提交
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