A.1h B.2h C.3h D.4h
A. “先薄后厚,先直后角” B. “先厚后薄,先直后角” C. “先直后角,先厚后薄” D. “先角后直,先厚后薄”
A.250~300mm B.200~250mm C.300~350mm D.>300mm