A) Football isn't my favorite sport.
Is football my favorite sport?
b) Brazilians aren't very friend.
Are brazilians very friend?
c) Norma and Sally aren't best friends.
Are Norma and Sally best friends?
d) My mother's name isn't Claudia.
Is my mother's name Claudia?
e) Italy and England aren't european countries.
Are Italy and England european countries?
f) Mr. Jones isn't the school principal.
Is Mr. Jones the school principal?
g) My (?) and I aren't classmates.
Are my (?) and I classmates?
(Coloquei uma interrogação na letra G pois creio que está faltando um nome!)
Lembrando que para o singular eu uso IS, e no plural: ARE.