Bonjour,
Réponse :
a. Barack Obama announced his candidacy.
announce verbe régulier on ajoute "ed"
b. Michelle Robinson married Barack Obama.
marry verbe régulier qui se termmine par "y", le "y" devient "i" + ed
c. A majority of American aged 45+ and 65+ chose Donald Trump as a president in 2016.
choose verbe irrégulier
d. Donald Trump became the 45th President of the US in 2017
become verbe irrégulier
