Phrasal verbs are composed of a verb + a preposition or adverb that changes the original meaning of the verb. For instance, a lot of phrasal verbs take the preposition “out.” Examples include break out (get away from), hand out (give to people), and, of course, make out (kiss a lot).
Some phrasal verbs are non-separable, meaning the preposition must directly follow the verb. For instance, you can say "I dropped by the bar," but not "I dropped the bar by" because drop by is non-separable.
On the other hand, drop off is separable. You can say, "I have to drop off my son at school," or, "I have to drop my son off at school."
Phrasal Verbs Grammar Quiz
Phrasal Verbs Lessons: