Question

the students prefer the new syllabus ___ the old​

Answer 1

the students prefer the new syllabus _over__ the old​.

•    the word "over" in the above sentence is a preposition
•   preposition is a word that precede a noun or a pronoun and establish a relation with another word or phrase.
•    the relation generally is about time ,place or direction.
•    without preposition , a sentence generally does not establish a meaning.
•   the preposition in the above sentence "over" establish a relation between the new syllabus and the old.