哦

ó nǐ shuō de dōu shì zhēn de

哦？你说的都是真的？

Oh? What you said is true?

ó shì zhè me huí shì ma

哦，是这么回事吗？

Oh, is that so?

ó jìng yǒu zhè děng shì

哦，竟有这等事！

Oh, how can it be!