extramann.机械手extraadj.额外的n.额外之物；临时演员adv.特别地extra excitation额外激发extramean effect超平均效应extralinguistics外部语言学extra hard twist高强捻Extra Dark Color特黑extra commission特别佣金extra-marginal[经] 超边际extra long valve超长翼extrancous risks附加险extrareal pelvis肾外型肾孟