电场作用下,电介质发生的极化现象中,发生于偶极子结构的电介质中,极化时间约10-2~10-10s;而且是非弹性的;需消耗一定能量的极化,称为()式极化。
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Which is NOT a distress signal ().
A continuous sounding with any fog signal apparatus
B. A signal sent by radiotelephone consisting of the spoken word Mayday
C. An International Code Signal of N.
D. The firing of green star rockets or shells