单项选择题
A position obtained by applying only your vessel’s coures and speed to a known position is a（）.
A.dead-reckoning position B.fix B.estimated position C.probable position D.running fix
单项选择题 A right-handed propeller will cause the survival craft to（）.
单项选择题 A sea anchor is（）.
单项选择题 A self-contained breathing apparatus is used to（）.
