Là (to be) in Vietnamese

Overview

The word "là" is the Vietnamese equivalent of "to be" but with a crucial limitation: it is used only for identity and definition, not for descriptions. This distinction is one of the first major conceptual hurdles for English speakers learning Vietnamese, because English uses "to be" for both identity ("I am a teacher") and description ("I am tired").

At the CEFR A1 level, understanding when to use "là" and when to omit it is fundamental. In Vietnamese, adjectives function as stative verbs, meaning they already contain the "to be" meaning within themselves. Saying "Tôi mệt" (I tired) is a complete, grammatically correct sentence meaning "I am tired" -- no "là" needed.

"Là" does not conjugate or change form. Like all Vietnamese verbs, it remains constant regardless of subject, tense, or number. This simplicity in form belies the conceptual adjustment English speakers must make regarding when it applies.

How It Works

Use "là" for identity/definition (noun complements):

Pattern	Example	Meaning
Subject + là + Noun	Tôi là giáo viên.	I am a teacher.
Subject + là + Noun Phrase	Đây là sách của tôi.	This is my book.
Subject + là + Name	Anh ấy là Nam.	He is Nam.

Do NOT use "là" with adjectives:

Pattern	Example	Meaning
Subject + Adjective	Cô ấy mệt.	She is tired.
Subject + Adjective	Trời nóng.	It is hot.
Subject + Adjective	Món ăn ngon.	The food is delicious.

Negation with "không phải là":

Positive	Negative
Tôi là sinh viên.	Tôi không phải là sinh viên.
Đây là nhà tôi.	Đây không phải là nhà tôi.

Examples in Context

Vietnamese	English	Note
Tôi là giáo viên.	I am a teacher.	là + noun (identity)
Đây là sách.	This is a book.	là + noun (definition)
Cô ấy mệt.	She is tired.	no là with adjective
Trời nóng.	It is hot.	no là with adjective
Anh ấy là bác sĩ.	He is a doctor.	là + profession
Đó là bạn tôi.	That is my friend.	là + noun phrase
Hôm nay là thứ hai.	Today is Monday.	là + day name
Không phải là tôi.	It is not me.	negated là
Đây có phải là nhà hàng không?	Is this a restaurant?	question form with là
Tiếng Việt là ngôn ngữ đẹp.	Vietnamese is a beautiful language.	là + noun phrase

Common Mistakes

Using Là with Adjectives

• Wrong: Tôi là mệt.
• Right: Tôi mệt.
• Why: Adjectives in Vietnamese function as stative verbs and do not need "là." Adding it creates an ungrammatical sentence.

Omitting Là with Nouns

• Wrong: Tôi giáo viên.
• Right: Tôi là giáo viên.
• Why: When equating the subject with a noun (identity/profession/definition), "là" is required.

Using Không Instead of Không Phải for Negation

• Wrong: Tôi không là sinh viên.
• Right: Tôi không phải là sinh viên.
• Why: Negating "là" requires the full form "không phải là" (or "không phải"), not just "không."

Usage Notes

In spoken Vietnamese, "là" can sometimes be heard in emphatic contexts where it would normally be absent, but this is a stylistic choice rather than standard grammar. In formal and written Vietnamese, the rule of reserving "là" for identity statements is strictly observed.

The distinction between "là" sentences and adjectival sentences maps roughly onto the linguistic concepts of equative clauses and predicative adjective clauses. This distinction exists in many Asian languages but is absent in English, French, and most European languages.

Practice Tips

• When constructing a sentence with "is/am/are," ask yourself: does the complement answer "what" (noun) or "how" (adjective)? Use "là" only for "what" answers.
• Practice converting English sentences: "She is a student" (là) vs. "She is smart" (no là). Build this reflex early, as it prevents a persistent error pattern.

Related Concepts

• Prerequisite: Personal Pronouns — pronouns serve as subjects in là sentences
• Next steps: Defining and Explaining — expand "là" into definition and explanation structures