45. A wave is transmitted along a string. Which of the following actions can quadruple the energy transmitted per unit time?
 I. double the frequency
 II. double the tension of the string
 III. double the amplitude
 IV. double the wave velocity
V. quadruple the frequency
 VI. quadruple the amplitude
(A) III, V
(B) II,Ⅲ, V
(C) I, VI
(D) I, III
(E) I, II, III

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統計： A(1), B(0), C(0), D(8), E(0) #2993344