存在等电点的电离平衡的表面活性剂是（）
A.两性离子表面活性剂
B.非离子表面活性剂
C.阳离子
D.阴离子
参考答案：A
It was at the school ______ was named after a hero ______ he spent his childhood.[ ]
A. which; that
B. where; where
C. that; where
D. which; where
（）电路类型标识符为NM。
A.网管监控等支撑系统
B.视频
C.同步链路电路（带业务）
D.同步链路电路（专用）
