单项选择题
A contra-guide is a type of（）.
A.bow thruster B.cargo gear C.steering engine D.rudder
单项选择题 A dead reckoning (DR) plot（）.
单项选择题 A deck fitting, used to secure line or wire rope, consisting of a single body with two protruding horns is called a（）.
单项选择题 A deepwell pump is a type of（）.
