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  3. Unlike the scientist, the engineer is not free to select the problem which interests him；he must solve the problems as they aris

Unlike the scientist, the engineer is not free to select the problem which interests him；he must solve the problems as they aris

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问题     Unlike the scientist, the engineer is not free to select the problem which interests him；he must solve the problems as they arise, and his solutions must satisfy conflicting requirements. Typically, the engineering solution to most problems must take into account many factors.
    To the engineer, efficiency means output divided by input. His job is to secure a maximum output for a given input or to secure a given output with a minimum input. The ratio may be expressed in terms of energy, materials, money, time, or man. Most commonly the denominator (分母) is money；in fact, most engineering problems are answered ultimately in dollars and cents.
    The emphasis on efficiency leads to the large, complex operations which are characteristic of engineering. The processing of the new antibiotic and vaccines in the test-tube stage belongs in the field of biochemistry, but when great quantities must be produced at low cost, it becomes an engineering problem.  It is the desire for efficiency and economy that distinguishes ceramic engineering from the work of the potter, textile engineering from weaving, and agricultural engineering from farming.
    Since output equals input minus losses, the engineer must keep losses and waste to a minimum. One way is to develop uses for products which otherwise would be waste. The work of the chemical engineer in utilizing successively greater fractions of raw materials such as crude oil is well known. Losses due to friction occur in every machine and in every organization. Efficient functioning depends on good design, careful attention to operating difficulties, and lubrication of rough spots, whether they are mechanical or personal.
    The raw materials with which engineers work are seldom found in useful forms. Engineering of the highest type is required to conceive, design, and achieve the conversion of the energy of a turbulent mountain stream into the powerful torque(转矩) of an electric motor a hundred miles away. Similarly many engineering operations are required to change the sands of the seashore into the precise lenses which permit us to observe the minute bacteria in a drop of water and study a giant mass of stars in outer space.  
The organization of the last paragraph can be best described as ______.
选项 A、following the time order
B、from specific to general
C、cause and effect
D、statement and examples
答案D
解析 由最后一段“The raw materials with which engineers work are seldom found in useful forms．Engineering of the highest type is required to conceive，design，and achieve the conversion of the energy of．．．into．．．Similarly．．．change the sands into．．．”可知，工程就是把看似无用的原材料转变为对人类有用的东西。然后举例说明，比如让山间急流转动百里外的发电机，把海滩沙砾变成望远镜观察太空等。
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