Translation of "Presume" in Japanese

I will not presume to give an opinion.

あえて意見を述べることはよしておこう。

I presume that he has paid the money back.

彼はお金を返したと思う。

May I presume to tell you that you are wrong?

失礼ですがあなたが間違っておいでです。

- I presume that he has paid the money back.
- I think that he repaid the money.

彼はお金を返したと思う。