哎呀！你这样做真是太不小心了。

Oh, dear! It was careless of you to do so.

youdao

他说：“你太不小心了！”

He said: "You can't be too careful!"

youdao

这架电视机由于使用太不小心而损坏了。

The TV set was damaged from rough usage.

youdao

So, if you by chance, I know it's very rare, but if by chance you don't get the class you can always follow up later.

如果你们偶然，我知道不太可能，但是如果不小心你们错过了某节课,你们就可以在之后补回来了。

麻省理工公开课 - 固态化学导论课程节选