单项选择题
A.1/2 B.1/3 C.1/4 D.1/5
A.40’~1°30’ B.1°30’~4°30’ C.4°30’~8° D.8°~15°
A.四爪单动卡盘 B.三爪自定心卡盘 C.一夹一顶 D.二顶尖