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问题 计算题

如图所示，高为h的车厢在平直轨道上匀减速向右行驶，加速度大小为a，车厢顶部A点处有油滴滴落到车厢地板上，车厢地板上的O点位于A点的正下方，则油滴落地点必在O点的左方还是右方？离O点距离为多少？

答案

解：设油滴离开车厢顶部时，车速为v0，油滴因惯性此时也具有水平速度v0，对地做平抛运动，油滴落到车厢上的时间为t，这段时间

油滴水平位移为x1＝v0t

车的水平位移为x2＝v0t－at2

油滴落在O点的右方，距O点△x＝x1－x2＝at2

而t＝得△x＝h

单项选择题

打(拔)钢板桩按设计图示尺寸以( )计算。

A．重量

B．面积

C．体积

D．防护面积
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单项选择题

A variety of illegal acts committed by people in the course of their employment, for their own personal gain, are collectively known as white-collar crime. Embezzlement, theft and trading securities (1) insider information are common forms of white-collar crime. The majority of cases involve low-level employees who steal because they are under (2) financial stress. Many plan to (3) the money back as soon as possible but may never do so. Their crimes are usually never (4) because the amounts of money are small, and no one notices the (5) .

(6) , there are some very large cases of white-collar crime, such as multimillion-dollar stock market or banking seams that take years to discover and are extremely difficult and expensive to (7) .

White-collar crime is not (8) to the business sector. Government employment, especially (9) the city level, also provides opportunities to (10) one’s pockets. (11) , building inspectors accept bribes and full-time employees receive (12) payments.

Although white-collar crime is less (13) than street crime, it involves (14) more money and harm to the public than crimes committed by street criminals. It is (15) that there are more criminals (16) the office suites than in the streets, yet the (17) of white-collar makes it difficult to uncover the offenses and pursue the offenders. As the economy (18) from manufacturing to services and electronic commerce, opportunities for white-collar crime (19) , while the technology needed to stop such crimes will (20) .

10（）

A.line

B.fill

C.pack

D.stuff
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