皮皮学，免费搜题
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【多选题】
紫外分光光度法检测药品时的操作注意事项有A.
色皿使用前须洗净并配对
B.
手拿比色皿毛玻璃面两侧
C.
装样品溶液的体积应至少为比色皿体积的1/2
D.
比色服如被污染可用络酸洗液清洗
E.
规定吸收峰±2nm处再测几点吸光度,核对吸收峰的位置是否正确
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反馈参考答案：
举一反三
【单选题】If the contacts of a motor starter or controller fail to drop out when the 'stop' button is depressed the _____.
A.
contacts are carrying excessive current
B.
contacts have become welded together
C.
shading coil is broken
D.
shading coil is loose
【单选题】Motor controller or starter contacts may become welded together if the contacts _____.
A.
open too quickly and arc
B.
close under excessive pressure
C.
open or close too quickly
D.
close under excessive starting current
【单选题】Motor controller or starter contacts may become pitted and welded together if the contacts _____.
A.
open under loaded conditions
B.
close slowly with light pressure
C.
open too quickly and arc
D.
close quickly with proportionate pressure
【单选题】Motor starter or controller contacts may become welded together if the contacts ( )
A.
open too quickly and arc
B.
close under excessive pressure
C.
open or close too quickly
D.
close under excessive starting current
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