backbarn.支承梁;托梁
backn.后面;背脊;靠背;后背;后卫vt.支持;后退adv.向后地adj.向后的;后面的;偏远的;过时的;积欠的
back-draft damper反向通风调节风门
backwash controller返洗液控制器
back on one's heels反向散射峰
back porch interval消隐脉冲后肩持续时间
backscattering echo后向散射回波
"offstage political meetings"
"Working backstage to gain political support for his proposal"
"many private deals were made backstage at the convention"
"costumes were changed backstage"