背反射环back: n. 1.背,背部;背脊;背面,反面;背后,后部,后面, ...ring: vt. (rang rung ) 1.鸣,敲(钟),摇( ...back reffection x ray examination: 背反射x-射线检验back reffection x-ray examination: 背反射x-射线检验back of ring: 活塞环内表面下载手机词典可随时随地查词查翻译