A:能表示突触结构的是①
B:②处兴奋时膜电位表现为外正内负
C:刺激②处时,③处可以测到电位变化
D:缩手过程中信息仅以化学信号形式传导
My grandfather began to use the computer in his ____(六十多岁).
48+42-36=____