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图中，两电极上发生的电极反应分别为：a极：Ag＋＋e－＝Ag           b极：Fe－2e－＝Fe2＋；下列说法不正确的是（   ）

A．a、b可能是同种电极材料

B．该装置一定是电解池

C．装置中电解质溶液一定含有Ag＋

D．装置中发生的反应方程式一定是Fe+2Ag+==Fe2++2Ag

答案

答案：B

题目分析：A、若为电解装置，阳极、阴极都可以是铁做电极，硝酸银作电解质，两个电极可以相同，正确；B、总反应为：Fe+2Ag+=Fe2++2Ag，为自发反应，所以该装置可以是原电池也可以是电解池，错误；C、由Ag++e-=Ag的电极反应可知，银离子参与放电，电解质溶液一定含有Ag+，正确；D、由a、b电极上的电极反应可知，发生的反应为：Fe+2Ag+=Fe2++2Ag，正确。

单项选择题

疑有肾下垂时应摄()

A．腹部仰卧位前后位片

B．腹部仰卧位斜位片

C．腹部侧卧位侧位片

D．腹部站立位前后位片

E．腹部俯卧位后前位片
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单项选择题

The idea of test-tube babies may make you either delighted at the wonders of modern medicine or irritated while considering the moral, or legal, or technological implications of starting life in a laboratory. But if you’’ve ever been pregnant yourself, one thing is certain: You wonder what it’’s like to carry a test-tube baby. Are these pregnancies normal Are the babies normal The earliest answers come from Australia, where a group of medical experts at the Queen Victoria Medical Center in Melbourne have taken a look at the continent’’s first nine successful invitro pregnancies. The Australians report that the pregnancies themselves seemed to have proceeded according to plan, but at birth some unusual trends did show up. Seven of the nine babies turned out to be girls. Six of the nine were delivered by Caesarean section. And one baby, a twin, was born with a serious heart defect and a few days later developed life-threatening problems.What does it all mean Even the doctors don’’t know for sure, because the numbers are so small. The proportion of girls to boys is high, but until there are many more test-tube babies no one will know whether that’’s something that just happened to be like that or something special that happens when egg meets sperm in a test tube instead of a fallopian tube. The same thing is true of the single heart defect. It usually shows up in only 15 out of 60,000 births in that part of Australia, but the fact that it occurred in one out of nine test-tube babies does not necessarily mean that they are at special risk. One thing the doctors can explain is the high number of Caesareans. Most of the mothers were older, had long histories of fertility problems and in some cases had had surgery on the fallopian tubes, all of which made them likely candidates for Caesareans anyway.The Australian researchers report that they are quite encouraged. All the babies are now making normal progress, even the twin with the birth defects.

What is the author’s tone in this passage

A．Depressed.

B．Optimistic.

C．Opposing.

D．Negative.
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