Export DGN file to DWG with Polyface mesh.

Hi everyone,

Could anyone help me?

At the moment, I am converting a DGN file (all elements are surface) to DWG file, I expect all elements are Polyface Mesh after converting.

I have tried so many time, Almost elements are Polyface Mesh after converting to DWG, however, there are still some are Polygon Mesh.

I have tried this way, Export and select setting as below:

Does anyone have any way could convert all to Polyface Mesh? I use this version 

Everyone can see here, both Polyface Mesh and Polygon Mesh after converting

Thank you so much.