程控用户交换机按技术结构可分为（）；（）两类。
参考答案：模拟交换机；数字交换机
构成动作电位主体部分的脉冲样变化称为（）
A.后电位
B.动作电位
C.峰电位
D.阀电位
E.静息电位
Having seen the movie adapted from an American novel, ______. A. the novel was read by him eagerly B. eagerly read the novel interested him C. he was eager to read the novel D. it was very eager for him to read the novel
