backward pig发育不良的仔猪backwardadj.向后的；落后的adv.向后backward supervision signal后向监视信号backward interval selection后向区间选择backward-curved blade fan后向曲叶式风机backward-acting regulator反向调整电路backward transter character反向传输特性backward integration method流场反演方法（反积分方法）backward glissade technique背向滑步技术backward unloading elevator后卸升运器backward-forward technique前推回推backward conditioning reflex倒行条件反射

1. The Pacific tilting disc check valve uses gravity to rapidly close the disc upon reversal of flow.
   美国太平洋翻转式阀瓣止回阀在出现逆流时利用重力迅速关闭阀瓣。