单项选择题
A.hydrography B.aids to navigation C.tidal currents D.regulatory boundaries
（）on still water indictes how loading weight distributi...
单项选择题（）on still water indictes how loading weight distribution affects on longitudinal strength.
A.Bending moment B.local strength C.shear force D.displacement
ANCHOR HAS ITS OWN CABLE TWISTED AROUND IT defines（）.A....
单项选择题ANCHOR HAS ITS OWN CABLE TWISTED AROUND IT defines（）.
A.foul of anchor B.dropping anchor C.weighing anchor D.walking back anchor
（）sends a radio signal from the bottom of the ship to t...
单项选择题（）sends a radio signal from the bottom of the ship to the sea-bed,from which it is reflected.
A.The marine sextant B.The chronometer C.The echo sounder D.The radar
