backingn.支持；背衬；伴奏动词back的现在分词.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Backcross-derived Lines后代衍生群体back-mix-flow reactor反向混流反应器,返混流反应器back-grouting technique后压浆backstroke turn indicator仰泳转身标志线back-arc foreland basin弧后前陆盆地back-projection imaging反投影成像Back-glissade push shot背向滑步推铅球back-of-an-envelopeadj.能快速容易地确定的；不需要复杂计算的back projection operation反投射运算backscattering properties后向散射特性