Detailed explanation
Multi-word verbs combine a lexical verb with one or more particles or prepositions. Their word order depends on the type of construction. A separable phrasal verb allows a noun object either before or after the particle: turn the volume down / turn down the volume. A pronoun object, however, must appear between the verb and particle: turn it down, not *turn down it*.
Inseparable prepositional verbs keep the verb and preposition together: look after the patient, rely on the evidence, deal with the complaint. Both noun and pronoun objects follow the complete combination: look after her, not *look her after*. The preposition introduces its complement and cannot normally be moved.
Three-part verbs contain a verb, a particle and a preposition: put up with, look forward to, come up with, talk someone out of. Most are inseparable as a whole, but some include an object position inside the pattern. Compare put up with the noise, where the object follows all three words, with talk him out of resigning, where the person appears between talk and out of.
Meaning cannot always be predicted from the individual words. Look into means investigate, bring about means cause, and carry out means perform. Learners should therefore record the grammar together with the meaning: carry out something / carry something out; look into something; put up with something; talk someone into doing something.
To check word order, replace the noun object with a pronoun. If the correct form is switch it off, the verb is separable. If the correct form is look into it, the combination is inseparable. For three-part patterns, consult the complete frame and identify whether a person, thing or action occupies each slot.
How to form it
Separable phrasal verb: verb + noun + particle or verb + particle + noun, but verb + pronoun + particle. Inseparable verb: verb + particle/preposition + noun or pronoun. Three-part verb: learn the complete frame, for example put up with + object, come up with + object, or talk + person + out of + -ing.