单项选择题
A marine chemist issues gas free certificates and is certified by which organization? （）
A.Mine Safety Appliance Association B.American Chemical Society C.Marine Chemists Association D.National Fire Protection Association
单项选择题 A major health hazard of the product tert-butylamine is that it （）.
单项选择题 A low pressure annular preventer which is used to direct flow of kick fluids away from the rig floor is called a （）.
单项选择题 A low HDOP (Horizontal Dilution of Precision) number such as 2 indicates a （）.
