I don't know why I do it.

我不知道我为什么这样做。

youdao

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

尽管我不知道这样做的道理，我仅会模仿着做。

youdao

Even I don't know why I do the things I do.

就是我自己，也不知道为什么会做我做的事。

youdao

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

VOA: special.2009.07.04

Some of you are probably going to be doctors and you don't know why I'm going to do special relativity or quantum mechanics, but you don't know when it will come in handy.

你们中的有些人可能会成为医生,但你们现在不能理解,我为什么要讲相对论和量子力学,但是说不定什么时候,你就用上了呢

耶鲁公开课 - 基础物理课程节选

What, you think I regret saving you? I can see that you do.I just... I don't know why.

VOA: standard.other

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 don't know why he'd do that, " the Shooter told Esquire.

CNN: The new story of the death of Osama bin Laden

But why risk associating my name with handing them over so long as I don't know what the Americans will do with them?

ECONOMIST: Iraq's post-war disorder