单项选择题
A.last part of the exhaust stroke, and the first part of the intake stroke
B.last part of the intake stroke only
C.early part of the injection stroke only
D.early part of the power stroke
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?（）
单项选择题 One method of constructing large marine diesel engines and reducing the total engine frame weight is through （）.