单项选择题
The lowest temperature at which the vapor formed from a liquid ignites and continues to burn steadily in the presence of an ignition source is called the （）
A.flash point B.fire point C.upper explosive limit D.lower explosive limit
单项选择题 Which of the following statements describes one of the functions of the ballast system?（）
单项选择题 The abbreviation "GM" is used to represent the （）
单项选择题 A segregated ballast system is a system where （）
