单项选择题
A.10%~20%B.20%~40%C.30%~40%D.30%~50%
A.宽13mm,齿距1.8mmB.宽12mm,齿距0.8mmC.宽12mm,齿距1.4mmD.厚0.64mm,齿距1.8mm
A.电熔对接焊机B.电动套丝机C.手动铰板D.割管器