A.180° B.120° C.360°
A.1-5-3-6-2-4 B.1-2-3-4-5-6 C.1-4-3-6-2-5
A.只有一處 B.有二處 C.都設(shè)置在曲軸前端 D.都設(shè)置在曲軸后端