2. 计算机
  3. Microwave communication uses high-frequency (1)______ waves that travel in straightlines throughthe air. Because the waves cann

Microwave communication uses high-frequency (1)______ waves that travel in straightlines throughthe air. Because the waves cann

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问题 Microwave communication uses high-frequency  (1)______ waves that travel in straightlines throughthe air. Because the waves cannot  (2)______with the curvature of the earth, they can be  (3)_____only over short distance. Thus, microwave is a good  (4) ______for sendingdata between buildings ina city or on a large college campus. For longer distances, the wavesmust be relayed by means of"dishes" or  (5)_____. These can be installed on towers, highbuildings, and mountain tops.
(1)______
A．optical
B．radio
C．electrical
D．Magnetic
选项 A、 
B、 
C、 
D、 
答案B
解析
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