单项选择题
A.velocity of current in knots
B.direction from which the current folws
C.estima ed current
D.direction toward which the current flows
单项选择题 The port clearance for a ship should be granted（）the completion of loading or discharging in the port.
单项选择题 The port gang way caught on a（）on the wharf and was severely damaged.
单项选择题 The present voyage of my ship began at the port of Shanghai after loading 8000 tons of cargo on board and ended after discharging the cargo at the port of Hong Kong, which is（）.