根据惠更斯一菲涅尔原理,若已知光在某时刻的波阵面为S,则S的前方某点P的光强度决定于

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问题:

根据惠更斯一菲涅尔原理,若已知光在某时刻的波阵面为S,则S的前方某点P的光强度决定于波阵面S上所有面积元发出的子波各自传到P点的()。

A.振动振幅之和

B.光强之和

C.振动振幅之和的平方

D.振动的相干叠加

考点:电气工程公共基础第二章物理学第二章物理学题库
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根据国家环保部的要求,自2011年7月1日起,所有生产、进口、销售的轻型汽油车、两用燃料车、单一气体燃料车必须符合()的要求。

A.欧III标准

B.欧IV标准

C.国III标准

D.国IV标准

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干式过滤器分为()。

A、固定筒式过滤器;

B、袋式过滤器;

C、拉西环式过滤器;

D、干带式过滤器。

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中国第一位女皇帝是:()

A、武则天

B、吕雉

C、妇好

D、冯太后

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Come on, my fellow white folks, we have something to confess. Out with it, friends, the biggest secret known to whites since the invention of powdered rouge: welfare is a white program. The numbers go like this: 61% of the population receiving welfare, listed as "means-tested cash assistance" by the Census Bureau, is identified as white, while only 33% is identified as black. These numbers notwithstanding, the Republican version of "political correctness" has given us "welfare cheat" as a new term for African American since the early days of Ronald Reagan.

Our confession surely stands: white folks have been gobbling up the welfare budget while blaming someone else. But it’s worse than that. If we look at Social Security, which is another form of welfare, although it is often mistaken for an individual insurance program, then whites are the ones who are crowding the trough. We receive almost twice as much per capita, for an aggregate advantage to our race of $10 billion a year--much more than the $3. 9 billion advantage African American gain from their disproportionate share of welfare. One sad reason: whites live an average of six years longer than African Americans, meaning that young black workers help subsidize a huge and growing "over-class" of white retirees. I do not see our confession bringing much relief. There’s a reason for resentment, though it has more to do with class than with race. White people are poor too, and in numbers far exceeding any of our more generously pigmented social groups. And poverty as defined by the government is a vast underestimation of the economic terror that persists at incomes--such as $ 20,000 or even $ 40,000 and above--that we like to think of as middle class.

The problem is not that welfare is too generous to blacks but that social welfare in general is too stingy to all concerned. Naturally, whites in the swelling "near poor" category resent the notion of whole races supposedly frolicking at their expense. Whites, near poor and middle class, need help too--as do the many African Americans.

So we white folks have a choice. We can keep pretending that welfare is black program and a scheme for transferring our earnings to the pockets of shiftless, dark-skinned people. Or we can clear our throats, blush prettily and admit that we are hurting too--for cash assistance when we’re down and out, for health insurance, for college aid and all the rest. Racial scapegoating has its charms, I will admit: the surge of righteous anger, even the fun--for those inclined--of wearing sheets and burning crosses. But there are better, nobler sources of white pride, it seems to me. Remember this: only we can truly, deeply blush.

The author is most critical of the whites’()

A. confession

B. hypocrisy

C.arrogance

D. hysteria

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通过祥子的悲剧,老舍表达了对社会、对祥子这样的下层百姓怎样的思想?

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