A.0.5mm B.1mm C.2~3mm D.3.5~4mm E.>4mm
A.1mm B.2~3mm C.3~4mm D.5~6mm E.7mm
A.輕輕接觸 B.緊密接觸 C.離開0.5mm D.離開1.5mm E.不能無壓力