【单选题】
When the wave period and the apparent rolling period are the same（）.
A、synchronous rolling occurs
B、roll period decreases
C、roll period increases
D、roll amplitude is dampened
查看正确答案
A、ensure penetration and distribution of the fuel in the combustion chamber B、ensure the needle valve is flushed clean during each injection C、prevent combustion gas blowback into the open needle valve D、prevent reflected pressure waves when the needle valve closes
