Irréguliers: how does être [to be] change?
ser-
Irréguliers: how does avoir [to have] change?
aur-
Irréguliers: how does aller [to go] change?
ir-
Irréguliers: how does faire [to do; to make] change?
fer-
Irréguliers: how does pouvoir [to to be able to] change?
pourr-
Irréguliers: how does vouloir [to want] change?
voudr-
Irréguliers: how does devoir [to must; to be obligated] change?
devr-
Irréguliers: how does venir [to come] change?
viendr-
Irréguliers: how does savoir [to know] change?
saur-
Irréguliers: how does voir [to see] change?
verr-
Irréguliers: how does falloir [to be necessary] change?
faudr-
Irréguliers: how does envoyer [to send] change?
enverr-