extracoden.附加码extraadj.额外的n.额外之物；临时演员adv.特别地extragalactic nebula河外星云extra long structure超长结构extracellular matrix细胞外基质extraocular antennae眼外触角extra-heart sounds额外心音extracorporeal liver离体肝extracellular solids细胞外固体extra ordinary state非常状态extra low-freezing超难冻extra galactic noise银河外噪声