单项选择题
A Doppler log in the volume reverberation mode indicates（）.
A.speed being made good B.speed through the water C.the set of the current D.the depth of the water
单项选择题 A Doppler log in the bottom return mode indicates the（）.
单项选择题 A deadhead is a(n)（）.
单项选择题 A barometer showing falling pressure indicates the approach of a（）.
