The verb BE in the present has 3 forms: am, is and are.
Positive - חיובי
I am a student. I'm a student.
We are happy. We're happy.
You are my friend/s. You're my friend/s.
They are at school. They're at school.
He is my brother. He's my brother.
She is my sister. She's my sister.
It is my dog. It's my dog.
Negative שלילי
I am not a student.
We are not happy.
You are not my friend/s.
They are not at school.
He is not my brother.
She is not my sister.
It is not my dog.
Questions שאלות
Are you a student?
Are you happy?
Are you my friend/s?
Are they at school?
Is he my brother?
Is she my sister?
Is it my dog?
The verb BE in the past has 2 forms: was and were.
I, he, she it + was(n't) - He was/wasn't my neighbor a few years ago.
We, you, they + were(n't) - They were/weren't at school yesterday.
Am - Is - Are www.english-4u.de
The Verb Be - Am/Is/Are www.eclecticenglish.com
The Verb Be - 6 tasks www.englishexercises.org
The verb be (am, are, is) - Exercise 3 www.englisch-hilfen.de
The forms of be (am, are, is) in English - Exercise 1 www.englisch-hilfen.de
The forms of be (am, are, is) - Exercise 2 www.englisch-hilfen.de
The Simple present of the verb "to be" www.myenglishpages.com/
Present simple - verb 'to be' (game) learnenglishkids.britishcouncil.org
Was / Were - Exercise 1 www.english-hilfen.de
Was / Were - Exercise 2 http://a4esl.org/
Was / Were - Exercise 3 http://a4esl.org/
Was / Were - Exercise 4 http://www.usingenglish.com/quizzes/77.html
Was / Were - Exercise 5 http://www.ego4u.com/
Was / Were - Video http://www.engvid.com/was-were/
Was/Were/Wasn't/Weren't - Wordwall Quiz 1
Was/Were/Wasn't/Weren't - Wordwall Gameshow Quiz
Was/Were/Wasn't/Weren't - Wordwall Quiz 2