Simple SQL/Database RDBMS Schema - Beginner Level - What Do You Think?

First of all, i'm glad to be part of your forum members! Hi to everybody...

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* represents primary key

As far as i see, this design is good. I need your confirmation I followed 1NF, 2NF, 3NF, and one to many relationships guidelines.

-Seller Table {*SellerID (number), first name (text), last name (text), address (text), city (text), CountryID (foreign key), phone number (text), date hired (date)}

-Customer Table {*CustomerID (number), first name (text), last name (text), address (text), city (text), CountryID (foreign key), SellerID (foreign key) }

-Car Table {*CarID (number), manufacturer (text), model (text), car year (text) }

-Purchased Car Table {*CarID (foreign key), *CustomerID (foreign key), date purchased (date)}

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These tables have multivalued fields...

Country Table {*CountryID (number), country name (text)}

A customer can store several phone number (home, cell, work):

Phone Table {*PhoneID (number), CustomerID (foreign key), phone number (text)}