题目内容：
（ ）The main idea of the third paragraph is that．
A．the mass of the fishDecides the intensity of electric power it generates B．the strength of shock givenBy a young electric ray can only light theBulb of apocket flashlight
C．to make full use of the energy producedBy electric fish，suitable wires shouldBeavailable
D．a mature torpedo is capable of producing enough electricity to knockDown a man
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答案解析：