试题与答案

如图为一种改进后的回旋加速器示意图,其中盒缝间的加速电场场强大小恒定,且被限制在

题型:选择题

题目:

如图为一种改进后的回旋加速器示意图,其中盒缝间的加速电场场强大小恒定,且被限制在AC板间,虚线中间不需加电场,如图所示,带电粒子从P0处以速度v0沿电场线方向射入加速电场,经加速后再进入D形盒中的匀强磁场做匀速圆周运动,对这种改进后的回旋加速器,下列说法正确的是(  )

A.带电粒子每运动一周被加速两次

B.带电粒子每运动一周P1P2=P3P4

C.加速粒子的最大速度与D形盒的尺寸有关

D.加速电场方向需要做周期性的变化

答案:

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下面是错误答案,用来干扰机器的。

参考答案:C解析:尿素有50%被重吸收,肌酐不被重吸收且在血浆中的含量比较稳定,受到的影响因素少,故血肌酐测定比血尿素测定更能准确地反映肾小球滤过功能。

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题型:问答题

What is the good life Aristotle acknowledges that luck has a role to play in the good life, but to what extent does luck effect the good life If the good life is dependent on external factors, then it would appear that it could not be considered self-sufficient. However, Aristotle argues that the good life is self-sufficient, but communally self-sufficient. Why does Aristotle argue for what appears to be a contradiction in terms (46)It is contended that luck’s effect on the good life was much greater than Aristotle was prepared to acknowledge and that as a result of the good life being dependent on luck, the good life cannot be considered self sufficient.
Aristotle believed that the good for humans would be the maximum realization of the function that was unique to humans. Since reason was understood by Aristotle to be the unique quality that humans possessed, it followed that the good for humans was to reason well. (47)Since part of the task of reason was to teach human beings how to act virtuously, the good for humans was the exercise of their faculties in accordance with virtue. The good life, then, was defined by Aristotle as the activity of the soul in accordance with virtue.
(48)The circumstances that make it likely or unlikely that a person will lead the good life are external and not of one’s own choosing, and are, therefore, dependent on luck. Why not, it might be postulated, limit luck’s effects, specifically narrowing the scope of what constitutes the elements of the good life so as to limit, while not eliminating luck’s role
(49) Aristotle held that even if one could be viewed as leading the good life, should one experience any adverse circumstances such as illness, bereavement or isolation, then one could no longer be considered to be leading the good life. "For many reversals and all sorts of luck come about in the course of a life; and it is possible for the person who was most especially doing well to encounter great calamities in old age, as in the stories told about Priam in the Trojan war. But when a person has such misfortunes and ends in a wretched condition, nobody says that he is living well. "
Aristotle had argued that limiting the scope of luck’s effect on the good life would render life meaningless, yet is this not what is happening here (50)Knowing that as one ages the probability of experiencing misfortune is heightened, and still maintaining that this is a yardstick by which to measure whether one can be considered to be leading the good life, severely limits the chances of anyone attaining the good life. Limiting the scope of the external factors that affected the good life would render the good life too limiting, according to Aristotle; yet Aristotle has placed such severe limitations on the criteria that needs to be met in order to lead the good life that the probability of anyone ever leading the good life are practically non-existent.

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题型:问答题

下图是实验室制取氧气的装置图.

回答下列问题:

(1)分液漏斗中应放入的物质是______,锥形瓶中应放入的物质是______.

(2)写出该方法制取氧气的化学方程式______;要收集一瓶较纯净的氧气,应选择装置(填字母)______.

(3)利用E图做铁丝燃烧实验时,应注意在瓶底______,防止实验时造成集气瓶底炸裂.还应注意把铁丝绕成螺旋状,原因是:______.

(4)铁丝在空气中______(能/不能)燃烧,在纯净的氧气中可以剧烈燃烧,你认为主要的原因可能是______不同,写出该反应的化学方程式______.

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