you could leave your response to the invitation slightly open-ended by saying you're not sure.

你可以表示你不确定，开放性地回复这个邀请。

I don't know 课堂 - SpeakingMax英语口语达人

Ask open-ended questions because these elicit a more descriptive response.

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Mr. Beyer said he doesn't fault Mr. Cuomo for the state's storm response, but said better communication could have ended the gas shortage days earlier, and helped to quell some of the panic that gripped New Yorkers when the shortage didn't immediately subside.

WSJ: Poor Training Fueled Gas Shortage After Sandy

The deal was ended four days after the killings, according to a letter released in response to an open records request.

WSJ: Conn., rifle maker end aid deal after killings