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问题 多项选择题

目前，管内铁路中间站机械室多数仅设一组地线，将提供给通信设备所需的（）和（）一起使用，对这种的方式使用的地线一般称为联合地线。

A.工作地

B.防雷地

C.普通接地

D.保护地

答案

参考答案：A, D

问答题

在图中画出浮在水面上的木块A所受力的示意图．
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单项选择题

It is quite reasonable to blame traffic jams, the cost of" gas and the great speed of modern life, but manners on the toad are becoming horrible. Eye,body knows that the nicest men would become fierce tigers behind the wheel. It is all right to have a tiger in a cage, but to have one in the driver’s seat is another matter.
Road politeness is not only good manners, but good sense too. It takes the most cool-headed drivers great patience to give up the desire to beat back when forced to face rude driving. On the other hand, a little politeness goes a long way towards reducing the possibility of quarrelling and fighting. A friendly nod or a wave of thanks in answer to an act of politeness helps to create an atmosphere of good will and calmness so necessary in modern traffic conditions. But such behaviors of politeness are by no means enough. Many drivers nowadays don’t even seem able to recognize politeness when they see it.
However, misplaced politeness can also be dangerous. Typical examples are the driver who waves a child crossing the street at a wrong place into the path of oncoming cars that may be not able to stop in time. The same goes for encouraging old ladies to cross the road wherever and whenever they want to.
An experienced driver, whose manners are faultless, told me it would help if drivers learnt to correctly join in traffic stream without causing total blockages that give rise to unpleasant feelings. Unfortunately, modern drivers can’t even learn to drive,let alone master the roadmanship. Years ago, experts warned us that the fast increase of the car ownership would demand more give-and-take from all road users. It is high time for all of us to take this message to heart.

It is not always right for drivers to______.

A. master roadmanship
B. recognize politeness when they see it
C. encourage old ladies to cross the road whenever and wherever they want
D. give a friendly nod in answer to an act of politeness
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