更多"Microwave communication uses high-f"的相关试题:
[单项选择]Microwave communication uses high-frequency (71) waves that travel in straightlines throughthe air. Because the waves cannot (72) with the curvature of the earth, they can be (73) only over short distance. Thus, microwave is a good (74) for sendingdata between buildings ina city or on a large college campus. For longer distances, the wavesmust be relayed by means of"dishes" or (75) . These can be installed on towers, highbuildings, and mountain tops.
A. optical
B. radio
C. electrical
D. magnetic
[单项选择]Microwave communication uses high-frequency (56) waves that travel in straightlines through the air. Because the waves cannot (57) with the curvature of the earth, they can be (58) only over short distance. Thus, microwave is a good (59) for sending data between buildings in a city or on a large college campus. For longer distances, the waves must be relayed by means of "dishes" or (60) .These can be installed on towers, high buildings, and mountain tops.
A. optical
B. radio
C. electrical
D. magnetic
[单项选择]
Microwave communication uses （） -frequency radio waves that travel in straightline sthrough the air. Because the waves cannot （） with the curvature of the earth, they can be （） only over short distance. Thus, microwave is a good （） for sending data between buildings in a city or on a large college campus. For longer distances, the waves must be relayed by means of "dishes" or （） . These can be installed on towers, highbuildings, and mountain tops.
Microwave communication uses （） -frequency radio waves that travel in straightline sthrough the air.
A. high
B. low
C. long
D. short
