单项选择题
A.早开早闭 B.早开晚闭 C.晚开早闭 D.晚开晚闭
A.气门早开早闭 B.气门晚开早闭 C.气门晚开晚闭 D.配气机构改变
A.5-15mm B.10-20mm C.15-25mm D.25-30mm