单项选择题
A.Stem B.Pin C.Box D.Stand
What is the best instrument for establishing a safe wor...
单项选择题What is the best instrument for establishing a safe working area before welding in a confined space? （）
A.An oxygen indicator B.A combustible gas indicator C.A combination combustible gas and oxygen indicator D.A flame safety lamp
What is the BEST conductor of electricity?（）A.Carbon di...
单项选择题What is the BEST conductor of electricity?（）
A.Carbon dioxide B.Distilled water C.Fresh water D.Salt water
Upon completion of fueling a gasoline driven vessel it ...
单项选择题Upon completion of fueling a gasoline driven vessel it is necessary to（）.
A.keep ports，doors，windows，and hatches closed B.start engines immediately C.ventilate before starting engine D.None of the above
