I really don't know why.

我真的不知道为什么。

youdao

I really don't know why I failed, I studied so hard!

我真的不知道为什么我没通过，我学习很刻苦啊！

youdao

I really don't know why anyone would give me an award.

我真搞不懂为什么每个人都奖励我。

youdao

Yes, I see them in the text just as anybody else does, but since I don't really know what they mean except by means of the translation, why should I use them?

我看着这些原版书，但是我也不懂他们真正什么意思,除了它们翻译过来的意思，所以我干嘛费劲去用俄语？

耶鲁公开课 - 文学理论导论课程节选

But for me, I like to look at something and just say, "I like this. I don't really know why though."

但对我来说，我喜欢看着某个东西，然后说，“我喜欢这个。但我也不知道为什么。”

关于现代美术 - SpeakingMax英语口语达人

which is, I don't know why I really wanted the tent, but I really, really did.

当时，不知道为什么我那么想要，但是确实很想要。

FAO Schwarz的回忆 - SpeakingMax英语口语达人

Like, even when I was 11, 12, I remember thinking, 'I want to pick really hard' I don't know why.

NPR: Mary Halvorson: Unorthodox, Jagged Jazz Guitar

It's really a great opportunity to be here -- I don't know why we didn't come all these years.

CNN: STORY HIGHLIGHTS

"I don't know anything - nobody really knows what will happen in 2010 which is why it's so exciting, " he said.

BBC: Hamilton challenge excites Button