单项选择题
A.bow and stern shell frames and plating B.junction of the frames with the beams and floors C.garboard strake,at each side of the keel D.thrust bearing of the main shaft
A.back current from the rudder B.greater pressure on the right or left side of the propeller,depending on rotation C.lower pressure on the right or left side of the propeller,depending on rotation D.torque from the velocity and angle at which the surrounding water impinges upon the propeller blades
A.compound plate B.furnaced plate C.flat plate D.rolled plate