I could do nothing but let go.
There was nothing I could do but to let go.
請問這兩句這樣寫文法正確嗎?
如果是的話，為什麼一句but後用原形，一句加to
謝謝

I could [do nothing] but [let go] 動詞片語對應動應動詞片語; There was [nothing I could do] but[to let go] 前面是名詞片語 後面得對應能有同樣功能的不定詞(或動名詞, probably)

非常感謝