电平不归零制 nrzl non-return-to-zero level: 不归零电平nrz-l non return to zero level: 不归零电平制alternating non-return-to-zero: 交替不归零制enhanced non-return-to-zero: 增强型不归零制non return to zero: 不归零制下载手机词典可随时随地查词查翻译