Fill in articles a, an, the where it is necessary Bill Robins was … very rich man. Do you know where … Mississippi is?

Bill Robins was а very rich man. (Уточнение).

Do you know where the Mississippi is? (Река).

The Amazon is in South America. (Река).

The Altai Mountains are higher than the Urals. (Горы).

The official name of the country is Ukraine. (Т.к. страну можно назвать республикой, то артикль не ставится).