Question

complete as sentenças usando as formas: am, is, are
a) he my friend
b)I at school
c)Mary a teacher
d) they good students
e) you my father

Answer 1

a) He is my friend
b) I am at school
c) Mary is a Teacher
d)they are good students
e) you are my father

O Verbo to be significa ser ou estar, e pra ser conjugado no presente afirmativo é bem simples: Tudo "are", exceto "i" e "he, she it"

I am
you are
he is
she is
it is
we are
you are
they are

e Mary, por exemplo, é Maria, e Maria é ela, portanto podemos substituir Mary por she. Então fica Mary is.
Caso você seja pequeno ainda, vou traduzir:
I (eu)
You (você ou vocês, depende do contexto)
He (ele)
She (ela)
It (coisa, ex: objetos, animais...)
We (nós)
You (nesse caso vai ser vocês, la em cima era você)
They (eles)

Enfim, espero ter ajudado

Answer 2

A) He is my friend.
B) I am at school.
C) Mary is a teacher.
D) They are good students.
E) You are my father.
Bons estudos!