“I swear” 한국어 표현이 있을까요?

혹시 이 영어 표현처럼 한국어 표현이 있나요? 아니면 가장 비슷한 의미가 뭘까요?

예를 들면:

“I could’ve sworn there was something I’d forgotten…”

“I swear that’s the truth!”

“I swear this is better than the other one”

저는 표현을 더 하고 싶은데 어떻게 하는지 몰라요.. 😂

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Is there perhaps a Korean expression that is like this English expression? Or what would be the most similar meaning?

For example:

(Up there lol)

I wanted to express myself more, but I don’t know how to… 😂