单项选择题
The device that allows a floating ship to sway without bending the marine riser system is the（）.
A.yaw joint B.sway joint C.slip joint D.flex or ball joint
单项选择题 The depth over a shallow patch，（）about 1．5 miles southeastward of Nanshan Tou lighthouse，reduces to 8 meters.
单项选择题 The danger associated with using carbon dioxide in an enclosed space is（）.
单项选择题 The bottom row of plating next to the keel of a lifeboat is known as the（）.
