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问题 单项选择题

咖啡因和茶碱共有的特征鉴别反应是

A.双缩脲反应

B.Vitali反应

C.Marquis反应

D.紫脲酸铵反应

E.绿奎宁反应

答案

参考答案：D

解析：

咖啡因和茶碱均系黄嘌呤类生物碱，紫脲酸铵反应是黄嘌呤类生物碱的特征反应。

单项选择题

当高压开关显示漏电、欠压，再次启动时必须按（）按扭。

A.试验 

B.复位 

C.补偿
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单项选择题

During his three years in office, the governor of a state has frequently been accused of having sexist attitudes toward women. Yet he has filled five of the nineteen vacant high-level positions in his administration with women appointees, all of whom are still serving. This shows that the governor is not sexist.
Which of the following statements, if true, would most seriously weaken the conclusion above

A．One of the women appointed by the governor to a highlevel position is planning to resign her post.

B．The platform of the governor’s political party required him to appoint at least five women to high-level positions.

C．Forty-seven percent of the women who voted in the state gubernatorial election three years ago voted for the governor.

D．A governor of a neighboring state recently appointed seven women to high-level positions.

E．(E) The governor appointed two Black Americans, two Hispanic Americans, and one Asian American to high-level positions in his administration.
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