Articles 17. Earth goes round Sun.
18. Do you know where Sahara Desert is situated?
19. Mom isn’t at home now. She is at work. She is doctor ant works
at hospital that is near our house.
20. Every summer we go to lake Issyk-Kul to rest.

17 THE Earth goes round THE Sun.

18. Do you know where THE Sahara Desert is situated?

19. Mom isn’t at - - - home now. She is at - - - work. She is A doctor and works

at THE hospital that is near our - - - house.

20. Every summer we go to - - - lake Issyk-Kul to rest.

--- с названиями озёр

The + планеты и названия пустынь

at - - - work, at - - - home... = устойчивые выражения без артикля

Конкретная больница возле дома = the

A / AN + профессия