erratic

他那反复无常的驾驶方式让大家都很紧张。

His ___erratic driving made everyone nervous.

她脾气的反复无常让所有人都感到疲惫。

Her ___erratic mood swings exhausted everyone around her.

他的工作表现很不稳定，时好时坏。

His work performance is quite ___erratic, sometimes good and sometimes bad.