A-A+

An ultrasonic sound__________. 查看材料A.is very l

2022-08-01 21:32:35 问答库阅读 167 次

问题详情

An ultrasonic sound__________. 查看材料
A.is very loud
B.does harm to people"s health
C.is produced by the hero in movies
D.cannot be heard by people请帮忙给出正确答案和分析，谢谢！

参考答案

正确答案：D
细节题。题干：超声__________。由第三段中的Innature，thereisactuallysoundthatisbeyondourhearing．Inphysics，thesoundthatexceeds20，000hziscalledultrasonic(超声波的)可知，自然界中，有种声音是听不到的(beyondourhearing)，因此超声是人们听不到的声音。故选D。