单项选择题
A.硬切换 B.软切换 C.接力切换
A.11.25 B.22.5 C.30 D.41.25
A.1,2,4,8,16 B.1,3,4,6,8,10 C.2,4,6,8,10,12 D.4,5,7,8,9,11