mercurial

他那善变的性格让同事们很难跟上他的想法变化。

His ___mercurial nature made it difficult for coworkers to keep up with his shifting thoughts.

厨师长喜怒无常的脾气让厨房员工永远不知道今天会碰上什么情绪。

The chef's ___mercurial temper meant the kitchen staff never knew what mood to expect.

山里的天气变化无常，几分钟内从阳光普照转为冰雹砸落。

The ___mercurial mountain weather swung from sunshine to hail within minutes.