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【单选题】
电流的频率不同,对人体的伤害程度也不同, 的交流电危害最大。A.
1 ～ 10Hz
B.
10 ～ 20Hz
C.
30 ～ 300Hz
D.
300Hz 以上
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【单选题】the idea of a fish being able to _____electricity strong enough to light lamp bulds(灯泡) is almast unbelievable.
A.
Generate
B.
Bring
C.
Create
D.
Shock
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