单项选择题
The color of the exhaust from a diesel engine should be （）
A.clear B.hazy light brown C.hazy light blue D.hazy light grey
单项选择题 Scavenging in a four-stroke/cycle diesel engine occurs during the （）.
单项选择题 The device allowing for the change in volume of the cooling water in a propulsion diesel engine closed cooling system is the （）.
单项选择题 Which of the following statements is true concerning an oil cooler?（）
