A.V1---V3 B.V3-V5 C.V5、I、aVL D.V1-V5 E.Ⅱ、Ⅲ、aVF
A.24 B.48 C.24~48 D.48~7 E.12
A.0.04s B.0.10s C.0.12s D.0.20s E.0.32s