在水面下面同一深处有两个点光源P、Q,能发出不同颜色的光,当它们发光时,在水面上

题型:选择题

问题:

在水面下面同一深处有两个点光源P、Q,能发出不同颜色的光,当它们发光时,在水面上看到P光照亮的水面区域大于Q光,以下说法正确的是   

A.P光的频率大于Q光

B.P光在水中的传播速度小于Q光

C.P光照射某种金属恰能发生光电效应,则Q光照射同种金属也一定能发生光电效应

D.让P光和Q光通过同一双缝干涉装置,P光条纹间的距离小于Q光

考点:双缝干涉薄膜干涉
题型:选择题

女性,67岁。房颤20年,右肾肿瘤切除术后5年,左侧剧烈腰痛、恶心、呕吐、尿少1天。查体:BP170/110mmHg,HR102次/分,神清,左肾区叩痛。实验室检查:尿蛋白2+,红细胞8/HP,尿比重1.020,血尿素氮15.5mmol/L,血肌酐352μmol/L,血钾5.5mmol/L,血钠130mmol/L,血钙2.1mmol/L,AST90U/L,血红蛋白125g/L,血小板正常。腹部平片未见结石征象。

该患者诊断为()

A.急性肾功能衰竭

B.急进性肾小球肾炎

C.急进性高血压

D.慢性肾功能不全,失代偿期

E.慢性肾功能不全,肾衰竭期

题型:选择题

判断昏迷最有价值的是()

A.角膜反射

B.能否被唤醒

C.瞳孔对光反射

D.吞咽反射

E.瞳孔散大

题型:选择题

我国的行政区域基本上划分为省、市、县三级。[ ]

题型:选择题

设f(x)和g(x)在[0,1]上连续,在(0,1)内可导,f(0)=f(1)=-1.

,试证至少存在一点e∈(0,1)使,
f′(ξ)+g′(ξ)[f(ξ)-ξ]=1.

题型:选择题

In opposing the 1970 Clean Air Act, the United States automobile industry argued that meeting the act’s standards for automobile emissions was neither economically feasible nor environmentally necessary. However, the catalytic converter, invented in 1967, enable automakers to meet the 1970 standards efficiently. Currently, automakers are lobbying against the government’s attempt to pass legislation that would tighten restrictions on automobile emissions. The automakers contend that these new restrictions would be overly expensive and unnecessary to efforts to curb air pollution. Clearly, the automobile industry’s position should not be heeded.
Which one of the following, if true, lends the most support to the automakers’ current position

A.The more stringent the legislation restricting emissions becomes, the more difficult it becomes for automakers to provide the required technology economically.

B.Emissions-restriction technology can often be engineered so as to avoid reducing the efficiency with which an automobile uses fuel.

C.Not every new piece of legislation restricting emissions requires new automotive technology in order for automakers to comply with it.

D.The more automobiles there are on the road, the more stringent emission restrictions must be to prevent increased overall air pollution.

E.(E) Unless forced to do so by the government, automakers rarely make changes in automotive technology that is not related to profitability.

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