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问题 选择题

如图甲所示，放在光滑水平面上的木块受到两个水平力F1与F2的作用，静止不动，现保持力F1不变，使力F2逐渐减小到零，再逐渐恢复到原来的大小，在这个过程中，能正确描述木块运动情况的图象是（　　）

A．

B．

C．

D．

答案

由于木块受到两个水平力F1与F2的作用而静止不动，故两个推力相等

假设F1=F2=F

力F2逐渐减小到零再逐渐恢复到原来的大小的过程中，合力先增大到F，在减小到零，故加速度也是先增大再减小，故C错误；

物体现在加速度增大的加速运动，再做加速度减小的加速运动，最后匀速运动，而速度时间图象的切线的斜率表示加速度，故A错误，B正确；

物体先做加速度不断变大的加速运动，再做加速度不断变小的加速运动，合力变为零后做匀速直线运动，与于位移时间图象的切线的斜率表示速度，而D选项图表示减速运动，故D错误；

故选B．

单项选择题

( )是治安案件查处程序中最重要的一个环节。

A．治安案件的调查
B．治安案件的侦查
C．治安案件处罚的决定
D．治安案件处罚决定的执行程序
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单项选择题

Just how does a person arrive at an idea of the kind of person that he is He develops this (1) of self through a gradual and complicated (2) which continues throughout life. The notion is an (3) that one establishes only with the help of others. (4) the elementary knowledge that one is short or tall is a comparative judgment that we cannot make (5) we have the opportunity to (6) ourselves with others. One’s idea of qualities which are harder to (7) is even more dependent upon other people’s ideas.

Whether one is intelligent, or stupid; attractive, or ugly; these and many other ideas of the self are (8) from the reactions of people with whom we (9) This process of (10) the nature of the self from the reaction of others has been labeled the "Looking-glass Self" by Cooley, who carefully analyzed this psychological (11) of self-discovery.

Just as the picture in the mirror gives an image of the physical self, (12) the perception of the reactions of others gives an image of the social self. We know, (13) , that we are good at certain things and not at others. This (14) came to us from the reactions of other persons, first our parents and then other individuals (15) in life. It should be remembered that, as other people’s reactions could be (16) and understood in more than one way, the looking-glass self with which the individual (17) may easily differ from the image others have actually formed of his (18) Clearly, it is our perception of the responses of others and not their (19) responses that (20) our self-image, and these perceptions are often not accurate.

4（）

A.Even

B.Only

C.But

D.Hence
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