hi everyone ,
I am a new learner so i have a lot of doubt . I have some questions .

1-" I looked at him " and "I laugh at him" in these sentences is the pronoun "him" direct object ? What is the reason of using preposition after verbs ? to transform intransitive verbs into transitive verbs ?

2- in the sentence " i wait for hours " the verb is wait and "for" is the preposition
but in this sentence " i wait for him" the verb is prepositional one "wait for"
How can i recognize the exact verbs ( wait vs wait for )in this kind of sentence ?

I hope that i could explain myself . Sorry for mistakes .
Thanks Yours sincerely