Question

1- rewrite the sentences using the contractive form.

a)- she is sister.
b)-you are my father.
c)- he is my brother.
d)- they are my teachers.
e)- we are Friends.

Answer 1

a) she's my sister

b) you're my father

c) he's my brother

d) they're my friends

e) we're friends

Answer 2

a) she's sister (acho que faltou algo nessa frase)
b) you're my father.
c) he's my brother.
d) they're my teachers.
e) we're friends 

are = pronome + ' + re
is = pronome + ' + s
am = pronome (no caso apenas I) + ' + s