I don't know why I bother! Nobody ever listens!

我不知道我干吗要浪费时间！根本没人听！

《牛津词典》

I don't know why I settled on Miami, but anyway I did.

我不知道为什么我落户到了迈阿密，但不管怎样我做了。

《柯林斯英汉双解大词典》

I don't know why I was so blunt.

我不知道自己为什么这么麻木。

youdao

I don't know why I do it. I just do it."

VOA: special.2009.07.04

.. I just don't--people don't like-- ... people would rather hate-- I don't know why it's something-- it wouldn't be a good movie theme, would it?

我不。。。人们不喜欢-,人们宁愿厌恶-,我不明白为什么-,那不是好的电影主题吗？

耶鲁公开课 - 金融市场课程节选

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

And I don't know why I do, except perhaps for what we'd named the dolls - toenail and fingernail.

NPR: Watching a Memory Shift over Time

"I was treated well, but I don't know why I was kidnapped, " Carroll said in a brief interview on Baghdad television.

NPR: Kidnapped American Reporter Jill Carroll Freed

Don't know why I ever thought I needed, don't know why I thought I needed, don't know why I ever thought I needed you.

NPR: Dustbin Bands: The Surreal McCoys