（20）ness and fitness. What would be the shape of the com-　bustion chamber？ Where should the valves be placed？　Should it have a long or short piston？ Such questions　have a range of answers that are supplied by experience，　by physical requirements， by limitations of available

　　（25）space， and not least by a sense of form. Some decisions，　such as wall thickness and pin diameter， may depend on　scientific calculations， but the nonscientific component　of design remains primary.　Design courses， then， should be an essential element

　　（30）in engineering curricula. Nonverbal thinking， a central　mechanism in engineering design， involves perceptions，　the stock-in-trade of the artist， not the scientist. Because　perceptive processes are not assumed to entail “hard　thinking，“ nonverbal thought is sometimes seen as a prim-

　　（35）itive stage in the development of cognitive processes and　inferior to verbal or mathematical thought. But it is para-doxical that when the staff of the Historic American　Engineering Record wished to have drawings made of　machines and isometric views of industrial processes for

　　（40）its historical record of American engineering， the only　college students with the requisite abilities were not engi-　neering students， but rather students attending architec-　tural schools.　It courses in design， which in a strongly analytical

　　（45）engineering curriculum provide the background required　for practical problem- solving， are not provided， we can　expect to encounter silly but costly errors occurring in　advanced engineering systems. For example， early models　of high-speed railroad cars loaded with sophisticated

　　（50）controls were unable to operate in a snowstorm because　a fan sucked snow into the electrical system. Absurd ran-　dom failures that plague automatic control systems are not merely trivial aberrations； they are a reflection of the　chaos that results when design is assumed to be primarily　a problem in mathematics.

　　21.In the passage， the author is primarily concerned　with

　　（A） identifying the kinds of thinking that are used　by technologists

　　（B） stressing the importance of nonverbal thinking　in engineering design

　　（C） proposing a new role for nonscientific thinking　in the development of technology

　　（D） contrasting the goals of engineers with those of　technologists

　　（E） criticizing engineering schools for emphasizing　science in engineering curricula

　　22.It can be inferred that the author thinks engineering　curricula are

　　（A） strengthened when they include courses in　design

　　（B） weakened by the substitution of physical　science courses for courses designed todevelop mathematical skills

　　（C） strong because nonverbal thinking is still　emphasized by most of the courses

　　（D） strong despite the errors that graduates of such　curricula have made in the development of　automatic control systems

　　（E） strong despite the absence of nonscientific　modes of thinking

　　23.Which of the following statements best illustrates　the main point of lines 1-28 of the passage？

　　（A） When a machine like a rotary engine mal-　functions， it is the technologist who is best　equipped to repair it.

　　（B） Each component of an automobile-for　example， the engine or the fuel tank-has a　shape that has been scientifically determined　to be best suited to that component's function

　　（C） A telephone is a complex instrument designed　by technologists using only nonverbal thought

　　（D） The designer of a new refrigerator should　consider the designs of other refrigerators　before deciding on its final form.

　　（E） The distinctive features of a suspension bridge　reflect its designer's conceptualization as well　as the physical requirements of its site.