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
单项选择题 Sidewise force of the propeller tends to throw a vessel’s stern to the right or left，depending on rotation. This force is caused by（）.
单项选择题 Shell plating that has curvature in two directions and must be heated and hammered to shape over specially prepared forms is called（）.
单项选择题 Panting frames are located in the（）.