If you offer him some help this time, since he once helped you, that would be ____.

A．equal

B．more equal

C．fairer

D．more fair

下列运算正确的是

A．（a+b）²=a²+b²

B．x³+x³=x⁶

C．（a³）²=a⁵

D．（2x²）（﹣3x³）=﹣6x⁵