用双2线-4线译码器74LS139及最少量的与非门实现下列逻辑函数。表是74LS139的功能表，图题是简化逻辑图。<br /> <img src="https://nimg.ppkao.com/2019-04/wuacheng/2019042714413996261.jpg?sign=d1fa1fde7da29ef91f1f1107d61ad82f&t=62d763a7" />