UNTAAn.联合国技术援助局UNabbr.(=United Nations) 联合国pron.<口>人，事物，家伙，东西undifferentiated spermatid未分化精子细胞unparallel-ruled surface非平行直纹面undeliverable import goods无法交付的进口货unparallel plate capacitor非平行板电容器uncooled IR imaging system非制冷式红外热像仪unconstitutional intention违宪的动机unmonitored control system无监视的控制系统,开环控制系统unmanned rotorcraft system无人直升机unbalanced electric bridge非平衡电桥unchannelized intersection非渠化式交通交叉口