こんにちは!

I'm having some trouble understanding why は is used in the following response,
instead of が. If someone could please help, I'd really appreciate it.

おさけ を のんだ こと **が** あります か / O sake o nonda koto ga arimasu ka? Have you ever
tried sake?

いいえ, おさけ を のんだ こと **は** あり ません / iie, o sake o nonda koto wa arimasen No, I've
never drunk sake.

Several people have pointed out that two previously similar questions answer
my question, but to me they don't. I'm still confused as to why が cannot be
used in the second sentence. Here, は is not used as contrastive, but neutral
so I now understand why it is used based on Naruto's response. But I still
don't understand why using が would be incorrect.

I have only learned hiragana and katakana so far, as I'm a newbie, so if
responses could take that into account, I'd really appreciate it.

ありがとうございます!
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2019-06-19T18:22:48.960
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2019-06-20T16:22:20.283
2019-06-20T16:22:20.283
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question
grammar word-choice usage
Koto ga arimasu vs. Koto wa arimasen