[ابو بيشو]

He refused to accept responsibility for his acts.
He refused to accept responsibility for his actions.
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The noun act is usually used when you want to comment on a particular
thing that someone has done: 'It was an act of great courage.' 'These
cowardly terrorist acts bring death and suffering to the innocent.'
When you are talking about someone's general behaviour, use actions:
'You can't be blamed for your parents' actions.' 'Her words and actions
have not gone unnoticed.'