To forget kindness and turn against righteousness; to be ungrateful and disloyal; to betray trust.
他曾受过许多帮助，如今却负恩背义，令人十分失望。
He had received a lot of help, but now he has forgotten kindness and betrayed trust, which is very disappointing.
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To forget kindness and turn against righteousness; to be ungrateful and disloyal; to betray trust.