A.at all timesB.in the bottom return modeC.in the volum……

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（）.

A.velocity of the current
B.bottom characteristics
C.depth of the water
D.speed over the ground

单项选择题A deadhead is a(n)（）.

A.tree or log awash in a nearly vertical position
B.crew member who refuses to work
C.upstream end of a land wall
D.buoy that is adrift

单项选择题A barometer showing falling pressure indicates the approach of a（）.

A.high pressure system
B.low pressure system
C.high dew point
D.low dew point

单项选择题（）the canal transit，the radar was operating.

A.At
B.In
C.During
D.With