短語詞組短語polygonal vortex line 折渦線polygonal line algorithm 多邊形算法polygonal line drum 折線卷筒convex polygonal line 凸折線simple polygonal line 簡單多邊形鏈circumscribed close polygonal line 圓內(nèi)接閉折線polygonal line setting 折線測設(shè)polygonal ultrasonic delay line 多角形超聲延遲線slope of polygonal line 折線邊坡 返回 polygonal line