About: I'm not sure

Many non native english speakers say

-I don't sure-👎

This might be because of the similarity in meaning with 'know'.

I don't know. 👍

However this is not correct, the meaning of 'sure' is much closer to 'certain'.

Use 'sure' in the same way you use verbs of emotion.

-angry 😡sad 😞happy😊 curious😮 scared 😱-

I don't happy👎

I'm not happy👍

Remember 'sure' is most commonly used in negative sentences.

I'm sure

is not as common as

I'm not sure.

Any questions, please ask :)