Question

fill with preposition
She has filed a complaint ------ CBI

Answer 1

Prepositions are referred to as the part of speech which intend to form a correlation between the subject and another part of a statement. They usually tell you about the object's position or time of action. Often placed before the subject (nouns, pronouns), they possess various meanings in different cases.

Anyhow, in the illustrated statement, there are possibilities of putting multiple prepositions, depending on what meaning one wants to provide the statement. Moreover, find the full statement with proper preposition below.

She filed a complaint "against" CBI.

Answer: against.

Answer 2

She has filed a complaint to CBI .