Plain of厄斯垂伊伦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-clothes officers便衣人员plain river network area平原河网区plain-and ball bearing滑动与滚动组合轴承Plain-breasted Piculetn.纯胸姬啄木鸟plain-line articulator铰链咬合架, 平线咬合架plain-wire-cut brick直切砖plain lead covered cable裸铅包电缆Plain-capped Brilliantn.纯顶星喉蜂鸟Plain Language Addresser语言朴素的讲话者plain-clothes policeman便衣警察