单项选择题
A.cylinders
B.exhaust valves
C.pistons
D.fuel valves
单项选择题 Diesel engines are started by supplying （） into the cylinders in the appropriate sequence for the required direction.
单项选择题 Diesel engines are started by supplying （） into the cylinders in the appropriate sequence for the required direction.
单项选择题 Cylinders of marine diesel engines are normally cooled by （）.