It has set us back in so many respects that I'm not sure how long it will take for us to catch up.

我们在很多方面都被延误了，不知道需要多久才能赶上。

《柯林斯英汉双解大词典》

They all look so alike to me that I'm never sure which is which.

它们在我看来简直一模一样，我永远分不清哪个是哪个。

《柯林斯英汉双解大词典》

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》

So someone returning from mass displacement, even though I'm sure are thrilled to be going home, they bring with them all sorts of challenges upon their return."

VOA: special.2011.07.06

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

So I'm not so sure I'm buying it.

NPR: New Hampshire Voters Shake Up the Race

So I'm not so sure that hard media scrutiny is going to come out as in normal times.

NPR: Week in Review: Superdelegates, Clemens Testimony

"As we get out here, we hear all the time, 'You know, I'm not so sure about voting for an African-American, '" he says.

NPR: 'Lunch-Bucket' Democrats Key in Pa. Primary