SER
Singular
1stP. Yo (I) (Soy)-Places
2^ tu (You) (eres)-you are
3rd^ usted (you,formal) (es) you are formal
       e'l (he,it) (es) he is,it is
       ella (she it) (es) she is,it is
Plural
1st Nosotros -as(we) (somos)=are
2nd IN Spain Vosotros -as (you) (sois)=are
3rd Ustedes (you) (son)=are
     ellos (they,M) (son)=are
     ellas (they, F) (son)=are

It's john's notebook
es el cuaderno de juan
It's the teachers paper
es el papel del professor
It's the student's book 
Es el libro del estudante
It's the students' book.
Es el libro de los estudante
IT's Mr Gomez's class
Es el clase de Senor Gomez
It's Diego's watch
Es el Reloj de diego
It's marta's cousin 
es la horario de lupe
It's Luisa's friend
Es la amiga de luisa
It's Raul's desk
Es el pupetre de Raul

They are Diego's relatives
Ellos son los parientes de Diego
They are diego's sisters
Ellos son las hermanas de Diego
The are diego's brothers
Ellos son los hermanos de Diego
They are Diego's teachers 
Ellos son los professors
They are diego's mother=father
ellos son los padres

?Eres tu americano?
Si, yo soy Americano
?Son Uds norteamericanos?
Nosotros somos norteamericanos
?Son Uds de Venezuela? 
Nosotros no somos de Venezuela