capricious

这一结论反复无常，毫无依据地变来变去。

The conclusion is ___capricious, changing without justification.

她的心情变化无常，一会儿高兴一会儿生气。

Her moods are so ___capricious that she can be happy one moment and angry the next.

他反复无常的性格让朋友们很难相处。

His ___capricious personality makes it difficult for friends to get along with him.