管子磨损分别主要发生在哪些部位?
参考答案:
管子的磨损多发生在省没器、过热器、再热器及燃烧器周围的水冷壁等处,尤以烟气走廊区、蛇形管弯头处、管子穿墙部位最甚。
计数资料
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