我不知道为什么这样说。

I don't know why to say so.

youdao

我不知道为什么这样回答总是逗得他们大笑。

This answer always made them laugh and I did not know why.

youdao

不，我不知道为什么这样设计的DSN僵硬的CDR制度。

And no, I don't know why DSN designed such an inflexible CDR system.

youdao

I don't know why they make that choice.

我不知道为什么他们做出这样的选择。

麻省理工公开课 - 固态化学导论课程节选

And it makes you want to go get that insurance. I don't know why, but it does.

这让你想去买这家保险。我不知道为什么，但这就是这样。

广告泛滥 - SpeakingMax英语口语达人