单项选择题
The joint of the riser in a marine riser system that compensates for heave，the up-and-down motion of a floater，is the（）.
A.flex joint B.slip joint C.heave joint D.riser joint
单项选择题 The athwartship hull structural members of a ship are（）.
单项选择题 The antennas of the trucks on deck are not fitted（）.
单项选择题 Ship’s steering gear refers to（）.
