单项选择题
Which of the following would cause a diesel to have black smoke?（）
A.leaky injector B.water in the gas C.too heavy oil D.water in the oil
单项选择题 Which of the following will take place if the clearance of the main bearings are excessive?（）
单项选择题 Which of the following will be the function of lubricating oil used in marine engines?（）
单项选择题 Which of the following may take place if the clearance of the main bearings are excessive?（）
