单项选择题

The British used radio waves because they______.

A．were more exact than sound waves
B．could not be detected
C．could penetrate fog and clouds
D．were easier to use than sound waves
<上一题 目录 下一题>
热门 试题

单项选择题
Sound waves reflected from a hill can be used to estimate______.
A．height of the hill
B．speed of sound
C．distance of the hill
D．intensity of sound
单项选择题
Practical application of this principle resulted in ______.
A．new electronic instruments for planes
B．new radio sets for RAF bombers
C．an electronic detecting device
D．a radio directing and ranging device
相关试题