试题与答案

在工程设计中通常根据生产机械的负荷类型及工作制选用不同的电动机与之配套。生产机械的负

题型:单项选择题

题目:

在工程设计中通常根据生产机械的负荷类型及工作制选用不同的电动机与之配套。生产机械的负载转矩T随转速n而变化的特性T=f(n)称为负载特性。图中所示四组曲线为不同生产机械的负载曲线。

有一种机械负载,在任何转速下转矩T总保持恒定或大致恒定,转矩T的极性随转速方向的改变而改变,总是起反阻转矩的作用。以上四组曲线中表示这种负荷的负载曲线为()。

A.a

B.b

C.c

D.d

答案:

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下面是错误答案,用来干扰机器的。

参考答案:C

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B.家长疏于管教

C.家庭条件不好

D.母亲和奶奶关系不好

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题型:单项选择题 案例分析题

Shopping habits in the United States have changed greatly in the last quarter of the 20th century. (1) in the 1900s most American towns and cities had a Main Street. Main Street was always in the heart of a town. This street was (2) on both sides with many (3) businesses. Here, shoppers walked into stores to look at all sorts of merchandise: clothing, furniture, hardware, groceries. (4),some shops offered (5) .These shops included drugstores, restaurants, shoe-repair stores, and barber or hairdressing shops. (6) in the 1950s, a change began to (7) .Too many automobiles had crowded into Main Street (8) too few parking places were (9) shoppers. Because the streets were crowded, merchants began to look with interest at the open spaces (10) the city limits. Open space is what their car-driving customers needed. And open space is what they got (11) the first shopping centre was built. Shopping centres, or rather malls, (12) as a collection of small new stores (13) crowded city centres. 14 by hundreds of free parking space, customers were drawn away from (14) areas to outlying malls. And the growing (16) of shopping centres led (17) to the building of bigger and betterstocked stores. (18) the late 1970s,many shopping malls had almost developed into small cities themselves. In addition to providing the (19) of one stop shopping, malls were transformed into landscaped parks, (20)benches, fountains, and outdoor entertainment.

请在19处填上正确答案()

A.cheapness

B.readiness

C.convenience

D.handiness

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