单项选择题
A.逻辑功能块 B.三次群模块 C.二阶模块TU D.最基本模块
A.STM-4 B.STM-1 C.TU-12 D.AU-3
A.A1A1A1A2A2A2 B.A1A2A3A1A2A3 C.A2A2A2A1A1A1 D.A1A2A1A2A1A2