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问题 选择题

如图所示，MN是一负的点电荷电场中的一条电场线，场强方向由M指向N，ab=bc，a、b、c三点的场强和电势分别为Ea、Eb、Ec和a、b、c，则下列关系正确的是：（ ）

A．Ea＞Eb＞Ec

B．Ea=Eb=Ec

C．a＞b＞c

D．a-b=b-c

答案

答案：C

由负电荷周围电场线分布可知，电荷在N点右侧，沿着电场线方向电势降低，距离电荷越近场强越大，由U=Ed可知C对；D错；

单项选择题

(三) Researchers have shown that noise can adversely affect human in both physiological and psychological ways. Hearing losses in particular occupations such as ship - building and con- structi - on work are well - known. In fact, however, we all find hearing more difficult as we age. Young ears can distinguish a wide range of sounds from low to very high frequencies, while older ears lose the ability to distinguish high -pitched sounds. A comparison of people living in some industrialized and non - industrialized areas suggests that this hearing loss may not necessarily accompany old age. Furthermore, a closer inspection of other data reveals economic effects. For instance, an increased turnover in property has been observed in noisy areas near airports. Job performance can be adversely affected by loud noise, especially if accuracy and mental effort are involved. The use of outdoor areas for conversation is not possible for an estimated 5 to 10 million people who live or work in urban areas. When interference with television or speech or sleep is included, as many as 22 to 24 million people can be said to have lost part of the use of their homes and grounds because of noise. Thus noise pollution is a serious environmental concern. The indifferent attitude toward noise should be overcome; considerable efforts should be made to alert people to the grave effects that may stem from an excessively noisy environment.

It can be inferred from the passage that loud noise has greater effects on people who work______

A．in ship -yards

B．in offices

C．at airports

D．on work sites
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单项选择题

在获取的下列审计证据中，可靠性最强的通常是（）。

A．被审计单位销售部会议记录

B．被审计单位提供的销售合同

C．债务人的电子邮件回函

D．前任注册会计师的工作底稿
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