Backas巴卡斯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-date倒填日期back fillet平嵌线back stress反应力,背应力back-like背越式back credit转开信用证back mixingn.回混back digger反铲挖土机back mirror后视镜back-heel脚后跟回传back filler回填机,填土机