Korean prepositions are actually postpositions because, unlike in English, they come after the word they modify.

Attach the locative particle 에 to the position word:

책상 위에 사과 있다 There is an apple on the desk.

• 사과는 책상 위에 있다

가방 속에 공책 있다 There is a notebook in the bag.

• 공책은 가방 속에 있다

• Prepositions Exam 1
• Prepositions Exam 2