A.圓形補(bǔ)強(qiáng)板 B.平形補(bǔ)強(qiáng)板 C.方形補(bǔ)強(qiáng)板 D.角形補(bǔ)強(qiáng)板
A.20mm B.30mm C.50mm D.60mm
A.40mm B.50mm C.20mm D.30mm