试题与答案

使用指针式绝缘电阻表测量时,手摇要保持匀速,不可过快或过慢,使指针不停地摆动,适宜的

题型:单项选择题

题目:

使用指针式绝缘电阻表测量时,手摇要保持匀速,不可过快或过慢,使指针不停地摆动,适宜的转速为()r/min。

A.120

B.100

C.180

D.60

答案:

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题型:填空题

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a. 上述由A生成D的单质的反应属于置换反应

b. D元素在自然界中主要以单质形式存在

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d. I是强电解质,G是弱电解质,二者的水溶液都显酸性

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题型:单项选择题

Which of the following, if true, would provide most support for concluding from the survey results described above that the use of illegal drugs by people below the age of 20 is declining

A.Changes in the level of drug use by high school seniors are seldom matched by changes in the level of drug use by other people below the age of 20.

B.In the past, high school seniors were consistently the population group most likely to use illegal drugs and most likely to use them heavily.

C.The percentage of high school seniors who use illegal drugs is consistently very similar to the percentage of all people below the age of 20 who use illegal drugs.

D.The decline revealed by the surveys is the result of drug education programs specifically targeted at those below the age of 20.

E.(E) The number of those surveyed who admit to having sold illegal drugs has declined even faster than has the number who have used drugs.

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