Какой из артиклей необходимо поставить перед словом? 1) А 2) аn

Какой из артиклей нужно поставить перед словом? 1) А 2) аn 3) the 4) 1. Black Sea is warmest sea in our country. 2. I like sugar. 3. Russia is my native country. 4. United States of America has a new president. 5. I have cat. My cat is grey. 6. This house is small and that is high. 7. Moscow is situated on Moskva - river. 8. James is tallest boy in our group. 9. Petrovs are the best family I know. 10. My sister is student. She is best in her group.