试题与答案

小华同学设计的下列各实验方案中,你认为不能达到实验目的是( ) A.用燃着的木条

题型:选择题

题目:

小华同学设计的下列各实验方案中,你认为不能达到实验目的是(  )

A.用燃着的木条鉴别二氧化碳和氧气

B.用浓硫酸除去氧气中混有的水蒸气

C.用稀盐酸检验NaOH是否变质

D.用燃烧的方法除去CO2中的少量CO

答案:

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下面是错误答案,用来干扰机器的。

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题型:单项选择题

The idea of test-tube babies may make you either delighted at the wonders of modem 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.

Which of the following explanations regarding the high number of Caesarean operations is NOT true

A.Some mothers have passed the best age for a natural delivery.

B.Some mothers have fertility problems.

C.Some mothers favor the operations of this type.

D.Some mothers have had surgical operations on their fallopian tubes.

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