Could you tell me what these three sentences have in common?
Mmmh... They are all conjugated with être?
Exactly! And can you see what is different?
Well... The subjects are all different.
Indeed! We have a feminine je, a masculine il and a feminine plural elles. Do you notice anything odd about the past participles there?
They are all written differently! Does that mean they can change depending on the subject?
Bravo, tu as trouvé!
Remember: conjugating a verb in the passé composé with être means you have to match the past participle to its subject!
Je and tu can either be masculine or feminine singular:
Je suis
→
monté·e
Tu es
→
monté·e
On depends on what it refers to (masculine or feminine, singular or plural), so do nous and vous (masculine plural or feminine plural):
On est
→
monté·es
Nous sommes
→
monté·es
Vous êtes
→
monté·es
Il(s) and elle(s) give away the gender and number pretty easily:
Il/Elle est
→
montée
Ils/Elles sont
→
montées
Watch out! The subjects je and tu can either be masculine or feminine. Same rule applies to nous and vous: they can either be masculine or feminine.
And the subject on can either be masculine, feminine and singular or plural!