1. Glasgow is situated on __the_ river Clyde. 2. The Nile flows across _the__ north-eastern part of Africa to the Mediterranean Sea. 3. Mr. Oliver was born on _the__ British Isles but now lives on one of _the__ islands in _the__ Pacific Ocean. 4. _The__Amazon is the longest river in the world. 5. __The_ Swiss Alps is _the__ best place for mountain skiing. 6. ___The_North Sea and ___the_ Atlantic Ocean surround __the__ British Isles. 7. What do you know about __the__ Sahara Desert? 8. When __the__ Titanic was crossing __the__ Atlantic she struck an iceberg. 9.___The_ highest buildings are in New-York. 10.__The___youngest boy has just started going to school; __the__ oldest boy is at college. 11. In __the__ second course they study History of __the__ USA. 12.__The___second day was like _the___ first. 13. February is ___the__ shortest month of __the__ year. 14. __The__ New Year begins on _the___ 1st of January. 15. __The__ largest open space in ___the__ West End of London is Hyde Park. 16. ___The_ young feel more free than __the__ old. 17. __The__ Prime Minister is __the__ most important person in Britain after __the__ Queen. 18 __The__ 22nd of June is __the__ longest day of __the__ year. 19. The landlord found the servants among __the__ poor.
Объяснять каждый случай употребления артикля письменно - этот надо пол-учебника здесь перепечатать. Нереально.