Crack Shirt blender model import problem

My model in Blender is just like.

But when i use .blend or export to .fbx, it look like this.

What should i do? I have searching for solution for hours.

Thank you for all advices.

*Edit for change a weird sentence

My first guess is that the poly faces are flipped.

Thank you for your advice.

I’ve search by the word ‘flip’.

And i find out how to make it solved.

just a normal flip the problem model.

Thank you very much.