Mmm, I'm not so sure that's a good idea.

嗯，我不知道这想法行不行。

《牛津词典》

Hmm, I'm not so sure.

噢，我不是很确定。

youdao

Mm, I'm not so sure.

嗯，我不太肯定。

youdao

So,basically,that's how I started. Sometimes I'm not sure if I've done the right thing or not."

VOA: standard.2010.07.20

Because,you know,you can't trust me,and so you have to check me out and make sure I'm not lying to you.

因为你不能相信我,你要弄清楚我是否对你们撒谎了。

耶鲁公开课 - 新约课程节选

So my walk is, it's not confident and I'm not sure if I'm strong in my step yet.

所以我的走姿不是特别自信，担心步伐会不稳。

I wonder if 实战 - SpeakingMax英语口语达人

The only problem is that I'm not so sure how to work the built-in DVD player.

WSJ: Dan Zevin: Driving in the Car With Dad

"I'm not so sure it's a bad strategy from where the NRA sits, " Grabowski added.

CNN: NRA draws heat over its new shooting game

Now I'm not so sure about the scarlet letter signs or the license plates identifying child molesters.

CNN: Commentary: A sex offender's scarlet letter