单项选择题
A diesel engine cooling water system with a pH factor of 30 indicates a condition of （）.
A.slight acidity B.slight alkalinity C.excessive alkalinity D.excessive acidity
单项选择题 Fuel injectors used in heavy fuel oil systems are usually provided with cooling to reduce（）.
单项选择题 The rate of fuel injection in a diesel engine cylinder depends primarily on （）.
单项选择题 The camshaft on a four-stroke/cycle diesel engine provides a means to operate the （）.
