单项选择题
Diesel engines obtain combustion air through turbo chargers，blowers，or（）.
A.air starters B.carburetors C.natural aspiration D.air receivers
单项选择题 Diesel engines are considered safer than gasoline engines because（）.
单项选择题 Before starting any diesel or gasoline engine，which of the following must be checked? （）
单项选择题 All marine low-speed diesels are of what design?（）
