单项选择题
A.at any location
B.on the drill floor and liquid mud handling areas
C.in bulk storage tanks
D.in machinery spaces
单项选择题 Antiseptics are used principally to（）.
单项选择题 An inflatable liferaft is floating in its container，attached to the ship by its painter，as the ship is sinking rapidly. Which action should be taken with respect to the liferaft container? （）
单项选择题 An indirect radar echo is caused by a reflection of the main lobe of the radar beam off the observer’s vessel. Which of the following is NOT a characteristic of indirect echoes? （）