【单选题】对数字基带信号波形中的单极性波形,下列哪种说法是错误的?
【单选题】当“0”、“1”等概时,以下码型的基带信号中既没有直流分量又有利于同步信号的提取的是 。
【单选题】Don't shout at the old man.They should ____.
【单选题】his old age,we didn’t invite him to climb the mountains with us. [ ]
【简答题】adv. being old and therefore valuable