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问题 单项选择题

下列关于管道系统说法错误的是（）。

A.管道系统是由人孔、手孔、管路三部分构成的。按照使用性质和分布段落分类，可分为用户管道和局间中继管道

B.主干管道一般用来穿放300对以上的主干电缆

C.在用户密度不高的地区，可以不作配线管道，而利用主干管道由于人孔或手孔引上电杆，采取架空配线方式

D.隧道适用于容量很大的市话局，多用在条数多、对数大的进局段落或主干路由上

答案

参考答案：B

单项选择题

To Err is Human


by Lewis Thomas
Everyone must have had at least one personal experience with a computer error by this time. Bank balances are suddenly reported to have jumped from $ 379 into the millions, appeals for charitable contributions are mailed over and over to people with crazy sounding names at your address, department stores send the wrong bills, utility companies write that they’re turning everything off, that sort of thing. If you manage to get in touch with someone and complain, you then get instantaneously typed, guilty letters from the same computer, saying, "Our computer was in error, and an adjustment is being made in your account."
These are supposed to be the sheerest, blindest accidents. Mistakes are not believed to be the normal behavior of a good machine. If things go wrong, it must be a personal, human error, the result of fingering, tampering a button getting stuck, someone hitting the wrong key. The computer, at its normal best, is infallible.
I wonder whether this can be true. After all, the whole point of computers is that they represent an extension of the human brain, vastly improved upon but nonetheless human, superhuman maybe. A good computer can think clearly and quickly enough to beat you at chess, and some of them have even been programmed to write obscure verse. They can do anything we can do, and more besides.
It is not yet known whether a computer has its own consciousness, and it would be hard to find out about this. When you walk into one of those great halls now built for the huge machines, and standing listening, it is easy to imagine that the faint, distant noises are the sound of thinking, and the turning of the spools gives them the look of wild creatures rolling their eyes in the effort to concentrate, choking with information. But real thinking, and dreaming, are other matters. On the other hand, the evidence of something like an unconscious, equivalent to ours, are all around, in every mail. As extensions of the human brain, they have been constructed the same property of error, spontaneous, uncontrolled, and rich in possibilities.

The first paragraph implies that ______.

A. computer errors are so obvious that one can hardly prevent it from happening
B. the computer is so capable of making errors that none of them is avoidable
C. computers make such errors as miscalculation and inaccurate reporting
D. Computers can’t think so their errors are natural and unavoidable
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多项选择题

放大器反馈的类型有（）。

A.正反馈和负反馈

B.直流反馈和交流反馈

C.电压反馈和电流反馈

D.前级反馈和后级反馈

E.串联反馈和并联反馈
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