plain to对 ... 是清楚的plainadj.清楚的；简单的；坦白的；平常的；朴素的；纯的n.平原；广阔的区域adv.完全地；纯粹地plain milling cutter平铣刀,平面铣刀,圆柱形铣刀plain cast iron roll平面铸铁轧辊plain round moulding纯圆饰plain end steel pipe平端钢管Plain-flanked Railn.纯胁秧鸡plain round tea tray素色圆茶盘plain taper sunk key普通锥形埋头键plain embossed design素色轧花plain jolting machine震实造型机plain medicative cart普通换药车