单项选择题
A.excessive ring action
B.excessive ring temperature
C.improper ring rotation
D.excessive ring face wear
单项选择题 Diesel engine electric starting motors generally require heavier duty motors and motors and operate at higher voltages than comparable starting motors for gasoline engines due to（）
单项选择题 The size of the exhaust valve opening is （）
单项选择题 If the piston groove drain holes for the oil control rings become clogged, which of the following is likely to occur?（）