单项选择题
A.the type of coolant
B.the design of the engine
C.the type of fuel to be burned
D.B and C
单项选择题 The sealing rings are in four parts and pressed together around the piston rods by means of （）.
单项选择题 The scavenging box is built of a number of sections provided with vertical flanges enabling them （） together to form two blocks.
单项选择题 The scavenging air ports are located at （） that they are just exposed by the upper edge of the piston when the piston is in the bottom dead center position.