I reviewed the suggestions sent previously, and I could not solve the problem. The problem is that the "country" field (country_id) disappeared from sight. And I added the field "Pais2" that created a column in the database other than "country". The problem is that the "country" field is not in invisible mode within odoo studio. And, I'm not allowed to delete the "Pais2" field that I created. In this link is the HTML code of the view.

https://drive.google.com/open?id=1xwz0YyCi7CcD_rOdbY9mt1wZRCBbGkAW