What is the difference when conjugating the verb retourner with être and avoir ?
The verbs that make up what we call "Dr. Mrs. Vandertramp", the ones conjugated with être, are only so when intransitive — when there is no object.
Elle est descendue du grenier.
Elles sont sorties ce matin.
Ils sont retournés en Angleterre.
Many of these verbs can also be used in a transitive way — they can act on another object.
When that happens, there are three differences:
- They are conjugated with avoir instead of être.
- Instead of the participle agreeing with the subject, the usual rules of object agreement apply.
- The meaning is usually different.
Elle a descendu le coffre du grenier.
→ Auxiliary is avoir, no agreement on descendu, means "brought down" instead of "came down".
Elles ont sorti leurs crayons de leurs étuis.
→ Auxiliary is avoir, no agreement on sorti, means "took out" instead of "went out".
Ils ont retourné leurs vestes.
→ Auxiliary is avoir, no agreement on retourné, means "turned around" instead of "returned".
You can check the different meanings in a dictionary like WordReference that gives the structure and some examples for each definition. Here's the entry for retourner. Let's compare two definitions:
The first definition in the picture is labelled vtr. That means verbe transitif, so those differences apply. It's conjugated with avoir, no agreement, and has the meaning "send back" at right.
The second definition is labelled vi for verbe intransitif. It's conjugated with être, does show agreement, and has the meaning "come back" at right.
There are actually lots of definitions for "retourner" as a transitive verb, so check out that entry!