单项选择题
Which of the following is a factor of fuel oil almost having nothing to do with the formation of combustion products?（）
A.setting point B.ash C.sulfur content D.carbon residues
单项选择题 Which of the following firing order may be used for an 6 cylinder engine?（）
单项选择题 Which of the following can be obtained by means of an indicator card?（）
单项选择题 Which of the following can be directly obtained by means of an indicator card?（）
