backward pig发育不良的仔猪backwardadj.向后的；落后的adv.向后backward transfer admittance反向转移导纳backward characteristic line后向特征线backward slides step shot put背向滑步推铅球backward-shifting technique后向平移技术backward vertical integration后向一体化backward wave oscillator tube返波振荡管backward Monte-Carlo method反向蒙特卡罗法backward-differnece formula反向差分公式backward bending supply curve向后弯曲供给曲线backward wave tube oscillator返波管振荡器