trừ khi

Unless

Level 3

Trừ khi means unless. It introduces the single exception that would change or invalidate the outcome of the main situation.

How It Works

1. Placement in the Middle
When placed in the middle of a sentence, trừ khi simply connects the main clause to the condition, just like in English:

  • [Main Clause] + trừ khi + [Condition]

2. Placement at the Beginning
If you start a sentence with trừ khi, directly translating English syntax (e.g., Trừ khi bạn học, bạn sẽ rớt) is grammatically acceptable and widely used. However, native speakers often prefer adding correlative conjunctions for better flow in two ways:

  • Flipping the logic: Use thì to connect the clauses and add mới to the main clause to mean "Only if X, then Y". Formula: Trừ khi [Condition] thì [Subject] mới [Action]. (e.g., Trừ khi bạn học thì bạn mới đậu - Unless you study, you won't pass / Semantic equivalent: Only if you study will you pass).
  • Adding a connector: Add nếu không thì (otherwise) before the main clause. (e.g., Trừ khi bạn học, nếu không thì bạn sẽ rớt). Vietnamese uses this as a correlative double-reinforcement (literally: 'Unless [Condition], if not [Result]') to help learners internalize the structure.

3. Negative Conditions
While English speakers often avoid negative verbs after "unless" because it creates confusing double negatives, Vietnamese freely uses negative verbs after trừ khi. For example, trừ khi trời không mưa translates to "unless it doesn't rain".

4. Trừ khi vs. Trừ
Do not confuse trừ khi (unless) with trừ (except). Trừ khi is generally followed by an action or state (a clause), though it is frequently followed by time-based noun phrases (e.g., trừ khi cuối tuần) due to the natural ellipsis of the copula là. Trừ is followed by a regular noun or pronoun.

5. Trừ phi vs. Trừ khi
You may sometimes hear or read trừ phi. Many people mistakenly believe this is a misspelling of trừ khi. In reality, trừ phi is the original Sino-Vietnamese loanword. The word phi comes from the Sino-Vietnamese root for 'not' or 'without' (as seen in phi + X), giving it a formal weight. They mean the exact same thing, but trừ phi sounds slightly more formal or literary.

6. Tense Flexibility
Unlike English, which restricts the future tense after "unless" (e.g., "Unless it rains", not "Unless it will rain"), Vietnamese allows tense markers after trừ khi. For example, trừ khi trời sẽ mưa (unless it will rain) is perfectly grammatical, though tense markers are often dropped for brevity.

Examples (5)

  1. Tôi sẽ đi, trừ khi trời mưa.

    I will go, unless it rains.

    Word by Word: I will go, except when sky rains.

    A straightforward usage where 'trừ khi' sits in the middle of the sentence.

  2. Tớ sẽ không tham dự bữa tiệc đó trừ khi cậu đi với tớ.

    I won't attend that party unless you go with me.

    Word by Word: I will not attend party that except when you go with me.

    Another natural example of 'trừ khi' connecting a main clause to a condition.

  3. Trừ khi tôi có nhiều tiền thì tôi mới mua nhà.

    Unless I have a lot of money, I won't buy a house.

    Word by Word: Except when I have much money then I just buy house.

    When starting with 'trừ khi', native speakers often use 'thì ... mới' to flip the logic to 'Only when I have a lot of money will I buy a house'.

  4. Trừ khi bạn xin lỗi, nếu không thì tôi sẽ không tha thứ cho bạn.

    Unless you apologize, I will not forgive you.

    Word by Word: Except when you apologize, if not then I will not forgive for you.

    Another way to start a sentence with 'trừ khi' is to use 'nếu không thì' (otherwise) to introduce the consequence.

  5. Dự án này sẽ thất bại, trừ phi chúng ta thay đổi kế hoạch.

    This project will fail, unless we change the plan.

    Word by Word: Project this will fail, except when we change plan.

    Using 'trừ phi', the formal Sino-Vietnamese variant of 'trừ khi'.

Common Mistakes

  • Using 'trừ khi' before a simple noun to mean 'except'.

    Tôi ăn mọi thứ trừ khi thịt.
    Tôi ăn mọi thứ trừ thịt.

    Because English speakers sometimes use 'except' and 'unless' interchangeably, learners often place 'trừ khi' before a noun. While 'trừ khi' can precede time-based noun phrases (like 'trừ khi cuối tuần'), it is generally followed by a clause. For regular nouns, use 'trừ' or 'ngoại trừ' (except).

  • Confusing 'trừ khi' with 'nếu không thì' (otherwise).

    Bạn phải học, trừ khi bạn sẽ rớt.
    Bạn phải học, nếu không thì bạn sẽ rớt.

    Learners sometimes use 'trừ khi' to mean 'otherwise' or 'if not' as a standalone connector. 'Trừ khi' means 'unless' and introduces a condition. To say 'otherwise', use nếu không thì.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

trừ khiLevel 3Unless

Learn This First

To understand 'trừ khi' (unless), you first need to be familiar with the basic word for 'when' (khi) and how Vietnamese handles conditional logic. It functions as a negative condition, similar to 'if not' or 'except when'.

Words in This Pattern

trừ phitrừ