Unkan温坎UNabbr.(=United Nations) 联合国pron.<口>人，事物，家伙，东西unrefined information未经提炼的情报unreservedly maintain毫无保留地坚持unexperimental method非实验方法unrecognizable option不可识别选择undeveloped districts欠发达地区undeserved reputation虚名undeveloped countries未开发国家unbalanced polyploidy不平衡多倍性Unmanned Air Breather安装空气喷气发动机的无人驾驶飞行器unpressurized feeding无压给料