单选题Sound is audible to human beings only if the frequency is______.A
fewer than about 20 vibrations per secondB
more than about 20,000 vibrations per secondC
about in a range of 20 to 20,000 vibrations per secondD
120 vibrations per second
题目
单选题
Sound is audible to human beings only if the frequency is______.
A
fewer than about 20 vibrations per second
B
more than about 20,000 vibrations per second
C
about in a range of 20 to 20,000 vibrations per second
D
120 vibrations per second