单项选择题
In a diesel engine cooling water system, a pH of 60 indicates a/an （）.
A.slightly acidic condition B.slightly alkaline condition C.overtreatment of water D.neutral condition of water
单项选择题 Which of the following statements concerning fire-tube boilers is correct?（）
单项选择题 A diesel engine cooling water system with a pH factor of 30 indicates a condition of （）.
单项选择题 Fuel injectors used in heavy fuel oil systems are usually provided with cooling to reduce（）.
