✅ We use "the" in the names with: Republic, Federation, State, Kingdom:
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The Russian Federation 🇷🇺
The USA 🇺🇸

✅ We use "the" with mountain chains (горные хребты, цепи, системы) ⛰🗻 ⛰🗻
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The Alps, the Urals, the Caucasus

✅ We use "the" with the group of islands 🏝 🏝
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The Bahamas, the British Isles.

✅ We use "the" in the names of:
Oceans: the Pacific (Ocean), the Indian (Ocean)

Rivers: the Volga, the Ob, the Thames, the Lena, the Mississippi

Seas: the Black Sea, the North Sea, the Baltic Sea

Channels: the English Channel, the Suez Channel

Deserts 🏜: the Sahara
Lakes: the Ontario, the Onega
❗️no article in the names "Lake".