Learn to Use 'To Be' in Negative Sentences (Pre-A1 English) — Pre-A1 English grammar lesson by Langcom

Learn to Use ‘To Be’ in Negative Sentences (Pre-A1 English)

Raúl Maguiña

Fundador de Langcom | Examinador de Cambridge y del SIELE

julio 19, 2026

PRE-A1✏️ Gramática⏱️ 3 minutos de lectura
To make a sentence negative with the verb to be in English, you simply add not after am, is, o are. This structure helps you say that something is not true, not present, or not a fact. For example, if you want to say you are not a doctor, you say I am not a doctor. We also use shorter forms, called contractions, which are very common in spoken English and informal writing. For is not, we often use isn’t. For are not, we use aren’t. And for I am not, the contraction is I’m not. Understanding these forms is a key step for Pre-A1 learners to express negative ideas clearly.

What is ‘To Be’ Negative?

The verb to be is very important in English. We use it to talk about who someone is, what something is, where someone is, or how someone feels.

When you want to say that something is no true, no present, or no a fact, you use the negative form of to be.

The basic rule is simple: add not after the form of to be.

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How Do We Form Negative Sentences with ‘To Be’?

The negative form of to be changes depending on the subject (who or what the sentence is about).

  • Para I, use am not.
  • Para he, she, it, or a singular noun (like the dog), use is not.
  • Para you, we, they, or a plural noun (like the students), use are not.

What Are Contractions with ‘To Be’ Negative?

Contractions are shorter ways to say words. They are very common in spoken English and informal writing.

Here are the contractions for the negative forms of to be:

  • I am not becomes I’m not.
  • He is not becomes He isn’t.
  • She is not becomes She isn’t.
  • It is not becomes It isn’t.
  • You are not becomes You aren’t.
  • We are not becomes We aren’t.
  • They are not becomes They aren’t.
Negative Forms of 'To Be' in Present Simple
Subject Full Form Contraction
I am not I’m not
He / She / It is not isn’t
You / We / They are not aren’t

Ejemplos

  • I am not tired.
  • She is not from Spain.
  • We are not at school today.
  • It isn’t cold outside.
  • They aren’t happy about the news.
  • My brother isn’t here.

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Errores habituales de los hispanohablantes

Spanish speakers sometimes make a common mistake by putting no directly before the verb, like in Spanish.

Incorrecto: I no am a student.

Correcto: I am not a student. o I’m not a student.

Remember, in English, not always comes after the form of to be (am, is, are).

Another mistake is confusing isn’t y aren’t. Always check the subject:

  • Uso isn’t for singular subjects (he, she, it, the book).
  • Uso aren’t for plural subjects (you, we, they, the books).

Preguntas más frecuentes

What is the rule for ‘to be’ negative?

The rule is to add not after am, is, o are. Por ejemplo, I am not, he is not, we are not.

Can I use contractions always?

You can use contractions like isn’t y aren’t most of the time, especially in speaking and informal writing. In very formal writing, it’s better to use the full forms (is not, are not).

What is the negative of ‘I am’?

The negative of I am is I am not. The common contraction is I’m not.

What is the difference between ‘is not’ and ‘isn’t’?

There is no difference in meaning. Is not is the full form, and isn’t is the contracted (shorter) form. They mean the same thing.

Sobre el autor: Raúl Maguiña

Raúl Maguiña es el director de la Asociación Educativa Langcom, un centro autorizado de preparación para el examen Cambridge English en EE.UU.. Con más de una década de experiencia en la enseñanza de idiomas y la certificación internacional, ha ayudado a miles de estudiantes, profesores e instituciones educativas de 25 países a conseguir las certificaciones de inglés de Cambridge, IELTS, TOEFL y Michigan.

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