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问题 选择题

如图，虚线所示的范围内有一匀强磁场，磁场方向垂直纸面向里，矩形线框abcd沿水平方向并自左向右匀速通过磁场．当线框通过图中①、②、③位置时，线框内的感应电流分别为i1、i2、i3，则（　　）

A．i1＞i3，i2=0

B．i1＜i3，i2=0

C．i1=i3＜i2

D．i1=i3，i2=0

答案

根据感应电流产生条件：穿过线圈的磁通量发生变化，所以当线圈完全进入时，线圈中没有感应电流．因此i2=0

而线圈正在进入磁场与正在离开磁场，导致磁通量发生变化，所以i1、i3都不等于零．

再根据切割磁感线产生电动势E=BLV与I=

E
R
可得：i1=i3．

故选：D

单项选择题

以太网物理地址的长度是______。

A．6bit

B．24bit

C．48bit

D．64bit
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填空题


In the following passage, there are 25 blanks representing words that are missing from the context. You are to put back in each of the blanks with the missing word. Write your answers on the ANSWER SHEET. The time for this section is 25 minutes.
Compared with the immediate practical responsibility of the scientist, the (1) of the artist must seem puny. The decision which faces (2) is not one of practical action: of course he will try to throw this (3) into the scale, and that weight, if he is a writer or (4) a painter of genius, may have its effect. For the novelist—in our society the only artist who has a mass audience and at the same time effective economic control of the means of addressing (5) —the hope of some decisive influence is a reasonable (6) . For him, since he takes of all artists (7) is probably the largest portion of his culture as material, there is no (8) escape from the necessity for treating the content of his work seriously than (9) is for the social psychologist he is coming so closely to resemble. The dichotomy which people have tried to establish between artistic proficiency and (10) content is becoming unbearable to almost all sensitive minds. I doubt if it has ever been real— we might have admired Shelley as (11) if he had been indifferent to such things as war and tyranny, though I doubt it; certainly (12) he been indifferent we should never have been led by (13) .
There is no Hippocratic oath in literature, and I am not attempting to draw (14) up. As far as I am concerned, the artist is a human being writ large and his (15) are the ethics of any human being. Perhaps I can best illustrate (16) seems to me the new (17) of those duties of assertion and refusal from one writer, and I do not (18) it is without significance that this (19) projects the whole situation of choice into a scientific parable, the (20) of a pestilence: a (21) many human (22) are called to fight against, called not by any supernatural (23) but by the simple fact that the fight against a plague is (24) like a biological human (25) .
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