【简答题】Radar is used to extend the ________ of man’s sense of observing his environment, especially the sense of vision. A) validity B) liability C) capability D) intensity
【单选题】In restricted visibility the speed of a vessel without operational radar may be ________ enable effective avoiding action to be taken on sighting another ship.
【单选题】The basic principle of radar is illustrated by what happens when one shouts in a e. The echoof the shouting 11 the walls helps a person determine the size of i cave. With radar, however , the waves ar...