In regard to your request for information, I regret to inform you that I am unable to help you.

关于你需要情报的事, 我遗憾地告诉你我没法帮助你.

《简明英汉词典》

I regret to say that I am unable to help you.

很抱歉,我爱莫能助.

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He has been unable to help us.

他未能从经济上资助我们.

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I regret being unable to help you.

我不能帮助你,深感遗憾.

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I regret being unable to help.

我帮不上忙甚为抱歉.

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