单项选择题
An example of a grade C product is（）.
A.naphtha，vm and p B.tridecanol C.cottonseed oil D.camphor oil
单项选择题 An example of a grade B product is（）.
单项选择题 An entry of water，gas，oil，or other formation fluid into the wellbore is called a（）.
单项选择题 An engine compartment gasoline fire requires which type of extinguisher?（）
