unkey[美俚]黑人老头子UNabbr.(=United Nations) 联合国pron.<口>人，事物，家伙，东西undisturbed plasma未受扰动等离子体unmanned satellite无载人的卫星unbalance quantity不平衡量unpopulated region无人居住区unbounded interval无界区间uncured propellant未固化推进剂undamped vibration无阻尼振动uncontrolled lines无控制线路unlabeled data set未标注集unrearranged virus非重排病毒