更多"Radio signals are waves that are us"的相关试题:
[单项选择]Radio signals are waves that are used to _________ music or speech.
A. transfer
B. transmit
C. transport
D. transform
[单项选择]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
[单项选择]If the radio waves had reached our planet one hundred years before, we would have______.
A. sent an immediate answer
B. sent an alarm against extraterrestrial attack
C. sent a short reply
D. sent no answer
[单项选择]The practical use of radio waves brought about______.
A. new machines for planes
B. a radio directing and ranging device
C. new radio sets for RAF bombers
D. a discovering device
[单项选择]The plane()radio signals for help until site crashed.
A. gave out
B. went out
C. handed over
D. ran out of
[单项选择]Sound waves reflected from a hill can be used to calculate the______.
A. Speed of sound
B. time between a sound and ifs echo
C. height of the hill
D. distance of the hill
[单项选择]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