短語詞組短語back wall of burner 小爐后墻back angle of scattering 反向散射back turning of head 鴟視back face of target 靶背面back out of contract 不履行合同;背棄合同義務(wù)back bone of head 腦杓back segment of profile 齒形背段back shroud of impeller [機]葉輪后蓋板back analysis of displacements 彈塑性位移反分析 返回 back of