backwardly往后地backwardadj.向后的；落后的adv.向后backward conditioning后向条件作用backward curved angle后弯角backward flow problem逆向流问题backward acceleration后向加速度backward heart failure充血性心力衰竭Backward spinning dive向后旋转跳水backward heat equation反向热传导backward recovery time反向恢复时间backward-curved vane后弯叶片backwardation contango交割延期费