我有时想这是一个大错。

I sometimes think that it is a great mistake.

youdao

我想这是一个大错误。

I think this was a BIG mistake.

youdao

这是一个大错误，我永远不会忘记的一个教训。

That was a mistake, and it was a lesson I would never forget.

youdao

这是一个大错误，我永远不会忘记的一个教训。

That was a mistake, and it was a lesson I would never forget.

youdao