单项选择题
Modern marine diesel engines equipped with mechanical fuel injection operate on a combustion phase within the cycle which is（）
A.entirely constant pressure B.entirely constant temperature C.a combination of constant volume and constant pressure D.a combination of constant temperature and constant pressure
单项选择题 The over-speed trip device installed in some diesel engines is automatically actuated by（）
单项选择题 The flywheel reduces speed fluctuations by （）
单项选择题 How often should the lubricating oil of a diesel engine be changed?（）
