Is the word after the verb in the verb phrase a preposition or an adverb

Is the word after the verb in the verb phrase a preposition or an adverb

There are prepositions and adverbs
Look at / for / about is a verb + preposition. If it is followed by an object, whether it is a pronoun or a noun, it should be placed after it
Look up / through turn on / off / up / down is a verb + adverb. If the object is a noun, it can be placed at the back or in the middle; if the object is a pronoun, it can be placed between the verb and adverb