输入序列是ABC，若输出序列变为CBA，经过的栈操作为【】。A.push,pop,push,pop,push,poppush,push,push,pop,pop,poppush,push,pop,pop,push,poppush,pop,push,push,pop,pop
A
push,pop,push,pop,push,pop
B
push,push,push,pop,pop,pop
C
push,push,pop,pop,push,pop
D
push,pop,push,push,pop,pop
