下面的式子中，相等的是请选择CBA7y+k6t.c)D/]+z1X7l,x-J5b6r8z4p
A．a2和2a)D/]+z1X7l,x-J5b6r8z4p
B．a+a和2a)D/]+z1X7l,x-J5b6r8z4p
C．a2和a+a)D/]+z1X7l,x-J5b6r8z4p