单项选择题
A major health hazard of the product tert-butylamine is that it （）.
A.can be absorbed through the skin B.causes irreversible damage to eye tissue C.is a very unstable product D.All of the above
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 （）.
单项选择题 A list signal of one white light indicates that the vessel is （）.
