V n to n
Structure information: Verb with Object and prepositional Object ComplementThe noun group following the verb is the Object, and the prepositional phrase is the prepositional Object Complement. This structure has a passive, with the pattern be V-ed to n. The prepositional phrase is the prepositional Complement. There are only three phrasal verbs with this structure, cut down, narrow down and whittle down. The active patterns are V n P to n and V P n (not pron) to n. The Object comes either between the verb and the particle, or after the particle. If the Object comes after the particle, it cannot be a personal pronoun. You say
The police narrowed it down to fouror
The police narrowed down their list of suspects to fourbut you do not say The police narrowed down it to four.The passive pattern is be V-ed P to n.