单项选择题
A.spring loaded line thrower
B.hand thrown buoyant line
C.shoulder-type line throwing gun
D.heaving line
单项选择题 Any vessel in need of carrying out deck washing must be（）by the department concerned beforehand.
单项选择题 An obstruction on a helideck is any object that might present a hazard to the（）.
单项选择题 AN ILLNESS PREFERABLY OF AN INFECTIOUS NATURE SEIZING MORE THAN TWO PERSONS ON BOARD AT THE SAME TIME defines（）.