单项选择题
The self-contained breathing device should not be used in which situation?（）
A.Oxygen deficient spaces B.Compartments containing poisonous vapors C.Fighting fires that produce heavy smoke D.Underwater search
单项选择题 The purpose of storm oil in a sea anchor is to（）.
单项选择题 The process of waiting a period of time before pretensioning an anchor is known as（）.
单项选择题 The most probable position of the object of a search at any given time is the（）.
