单项选择题
After reporting a casualty to a mobile offshore drilling unit，which record must be retained on board? （）
A.Record of drafts B.Hull reports C.Anchor record D.Machinery repair book
单项选择题 After putting on a self-contained breathing apparatus，you open the air supply and hear a continuous ringing of a bell. What does this mean? （）
单项选择题 According to the Chemical Data Guide，epichlorohydrin is a(n)（）.
单项选择题 A space should be ventilated when（）.
