关于声音的发生，下列说法中正确的是（ ）
A．振动的物体都能够发出声音
B．我们听到的声音一定是由物体振动产生
C．振动慢的物体不能发声，振动快的物体能发声
D．因物体的材料、结构不同，所以有的物体振动时能发声，有的物体振动时不能发声
A、振动的物体都可以发生声音，只是有时缺乏传声的介质或频率不在人的听觉范围内而使我们听不到声音，故A正确；
B、物体振动，人们才可能听到物体发出的声音．正确．
C、不论振动快慢，都可以发出声音．错误．
D、不同材料、结构的物体振动，也都可以发声．错误．
故选AB．
| 补全对话：选择方框内适当的选项填入短文空白处(有一项是多余的)。 | |
| A: What are you doing? B: 1 A: Great! Can you tell me something about the book? B: Certainly! It sa  ys 1,000 years ago, the world's population was very small. 2  A: Really? B: Yes, but during the last three or four hundred years, the world's population has grown very quickly. Today, it is growing faster than ever before. 3 A: Sorry, I don't know. B: It's more than 6 billion. A: It's so big. 4 B: Yes. If we don't control the population, there will not be enough space even to stand in on the earth in 600 years. A: 5
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