Monsieur, quand est-ce que vous êtes part .. "i" OR "is"

Question

Please can you explain the ending of the word "partir" for me in this instance? I put "is" and it was incorrect, many thanks, Marie

Accepted Answer

Hi Marie, 
With Monsieur, at the beginning of the sentence, it indicates that the 'vous' polite form is used and there is no agreement of the past participle as this vous is 'singular'.
For revision take a look at this Kwiziq lesson on the different forms of 'you' in French -
https://french.kwiziq.com/revision/grammar/tu-and-vous-are-used-for-three-types-of-you
Bonne Continuation!

Answer

Monsieur implies polite singular meaning -- not plural in this instance.

Therefore vous êtes parti is appropriate. Normally you may expect the past participle to reflect plural usage but that is not always the case.