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问题 选择题

用足量的氢气在加热条件下还原氧化铜，当完全反应后测得生成铜的质量为64克，则消耗掉氢气的质量（　　）

A．小于2克

B．等于2克

C．大于2克

D．无法确定

答案

设参加反应的氢气的质量为x

H2+CuO

  △  
.
 
Cu+H2O

2         64

x         64g

2
x
=
64
64g

x=2g

因为还原之前要先通氢气，反应结束后还要继续通氢气，直到试管冷却．所以实际用的氢气要大于参加反应的氢气．

故选C

单项选择题

High-technology medicine is driving up the nation’s health care costs. Recent advances in cataract surgery illustrate why this is occurring. Cataracts are a major cause of blindness, especially in elderly people. Ten years ago, cataract surgery was painful and not always effective. Thanks to the new technology used in cataract surgery, the operation now restores vision dramatically and is less expensive. These two factors have caused the number of cataract operations performed to increase greatly, which has, in turn, driven up the total amount spent on cataract surgery.
Which one of the following can be inferred from the passage

A．Ten years ago, few people had successful cataract surgery.

B．In the long run, the advantages of advanced medical technology are likely to be outweighed by the disadvantages.

C．The total amount spent on cataract surgery has increased because the increased number of people electing to have the surgery more than offsets the decrease in cost per operation.

D．Huge increases in the nation’s health care costs are due primarily to increased demand for surgery for older people.

E．(E) Ten years ago, cataract surgery was affordable for more people than it was last year.
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单项选择题

男性，65岁。颅脑术后第5天，已持续高热4天，全身水肿，近3天每日尿量50～100ml，尿比重1．010，BUN36．4mmol／L（102mg／dl），血Cr724μmol／L（8．2mg／dl），SBE-5．1mmol／L（7．2mEq／L）。应进行下列哪项处理（）

A.碳酸氢钠静脉点滴

B.快速补液，以纠正肾灌注不足

C.静点甘露醇

D.血液透析

E.呋塞米（速尿）40mg静脉注射
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