单项选择题
What can be used to measure the percentage of oxygen inside a chain locker?（）
A.Flame safety lamp B.Combustible gas indicator C.Oxygen indicator D.H2S meter
单项选择题 What best describes an anchor buoy?（）
单项选择题 What are the two main types of stud link chain?（）
单项选择题 What action should you take to compensate for the abovecurrent?（）
