2. There are two tuning forks with frequencies 255 Hz and 251 Hz. When both tuning forks start vibrating, what frequency will be heard by the ear? How many times per second can a loud sound be heard?
(A) 251 Hz, 2 times each second
(B) 255 Hz, 4 times each second
(C) 254 Hz, 3 times each second
(D) 253 Hz, 4 times each second
(E) 252 Hz, 2 times each second
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統計: A(0), B(0), C(0), D(2), E(0) #3421197
統計: A(0), B(0), C(0), D(2), E(0) #3421197