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 white cast iron普通白口铸铁plainly worded labels措词简明的标签plain food/cooking清淡的食物/烹饪plain shedding tappet平纹开口踏盘plain paper facsimile普通纸传真机plain surface grinder平面磨床plain concrete lining素混凝土衬砌plain-barreled roll平辊plainline articulator铰链牙合架, 平线牙合架plain-break breaker直接熄弧断路器