单项选择题
What is the female section of a tool joint called? （）
A.Stem B.Pin C.Box D.Stand
单项选择题 What is the best instrument for establishing a safe working area before welding in a confined space? （）
单项选择题 What is the BEST conductor of electricity?（）
单项选择题 Upon completion of fueling a gasoline driven vessel it is necessary to（）.
