单项选择题
A life float on a fishing vessel must be equipped with （）.
A.a painter B.red smoke flares C.a jackknife D.a signal mirror
单项选择题 A life preserver or buoyant work vest is required to be worn on a ship when a person is （）.
单项选择题 A latitude line will be obtained by observing a body （）.
单项选择题 A lashing used to secure two barges side by side，lashed in an "X" fashion，is called a （）.
