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

问题:

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

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题型:单项选择题

(12分)化合物A是制玻璃的主要原料之一。常温下,化合物B、H、I为气体,B不溶于水,H、I易溶于水,H的水溶液呈碱性,I的水溶液呈酸性。D元素是地壳中含量仅次于氧的非金属元素。化合物J是一种可用于制造发动机的新型无机非金属材料,其相对分子质量为140,其中D元素的质量分数为60%。上述物质间的转化关系如下图所示。

(1)除A外,制玻璃的主要原料还有物质(填化学式)              

盛放NaOH溶液的试剂瓶不能用玻璃塞,原因是(用化学方程式表示)       

(2)D元素在元素周期表中的位置是           

(3)H的电子式是         

(4)F和H反应生成J和I反应的化学方程式是           

(5)下列说法正确的是(填选项序号)      

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

c. G是含有极性共价键的离子化合物

d. I是强电解质,G是弱电解质,二者的水溶液都显酸性

题型:单项选择题

高脂肪配方膳食适合于()。

A.肝功能衰竭的患者

B.胃肠道消化功能障碍的患者

C.肾衰竭的患者

D.肺功能受损的患者

E.先天性氨基酸代谢缺陷症的患者

题型:单项选择题

全身或局部使用可使泪管发生阻塞的药物包括()

A.碘胺类药物

B.氟尿嘧啶类药物

C.碘苷类眼药水

D.头孢类药物

E.氨基苷类药物

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.

题型:单项选择题

某企业只生产一种产品,200X年期初存货是20000元,期末存货是0。在这种情况下,按完全成本法确定的经营净利润比按变动成本的净利润()。

A.小

B.大

C.大或小

D.相等。

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