ruthless

他以无情的野心追求自己的目标。

He pursued his goals with ___ruthless ambition.

那个无情的独裁者镇压了所有反对派。

The ___ruthless dictator suppressed all opposition.

他无情的野心驱使他背叛了自己最亲密的盟友。

His ___ruthless ambition led him to betray his closest allies.