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must have to
must have to

Modals – Must & Have To

Confused about when to use ‘must’ and ‘have to’? In this video, we’ll simplify the differences between these two modals and explain when to use each one. Whether you’re expressing necessity, giving strong advice, or talking about obligations, understanding ‘must’ and ‘have to’ is key for clear communication. We’ll cover examples, compare usage, and help you avoid common mistakes so you can use these modals with confidence. Perfect for English learners at all levels looking to improve their grammar skills!

Grammar

Modals

Practice how to use Must & Have To.

Practice pdf

Must

Mustn’t & Don’t Have To

Practice with answers pdf

Must with Answers

Mustn’t & Don’t Have To with Answers

Transcript

Watch Our Video!

Introduction:

  • Host: Hello and welcome to the English Magnet. Today’s video: Must & Have To Made Easy! Though they express similar ideas, these verbs also play unique roles in English! “Must” is a modal verb, while “have to” is not, so knowing their formations and specific roles is crucial. Consequently, we’ll go over each one’s structure, uses, and common mistakes to watch out for. Obviously this video is a must! 😉 Let’s get started!

Part 1: Structure of Must

Since “must” is a modal verb, it means it’s followed by the base form of another verb. Let’s look at different structures:

Positive: Subject + must + base form 

Example: We must lock the door when leaving. 

Negative: Subject + must + not + base form 

or the contraction mustn’t (mustn’t is plugged in instead of must not) 

Example: You must not forget to submit your application by the deadline. or You mustn’t forget to submit your application by the deadline. 

Question: (Question word) + Must + subject + base form + ? 

Feel free to add a question word at the beginning of your question (question word is added) 

Example: (Why) Must I finish the project by tomorrow?

You can also go for a negative question: 

Example: Must we not inform everyone before making a decision? or with a contraction: Mustn’t we inform everyone before making a decision?

As you can see, ‘must’ doesn’t change form since it’s a modal! (except for forming mustn’t in the negative form)

Part 2: Structure of Have To

While ‘have’ and ‘have to’ express different meanings, their structures are pretty much the same. This means that if you know how to conjugate ‘have’ you can conjugate ‘have to’. Structure wise, the main difference is that ‘have to’ is a semi-modal verb and it’s followed by a verb in its base form. Let’s look at some forms. 

Positive: Subject + have/has to + base form
Example: She has to finish her work on time.

Negative: Subject + don’t/doesn’t + have to + base form

Example: She doesn’t have to attend the meeting. 

If the contraction is not your thing, go without: She does not have to attend the meeting. 

Question: (Question word) + Do/Does + subject + have to + base verb?

Example: Do you have to leave early?

You can also form a negative question by using don’t or doesn’t (they replace do/does)

Example: Don’t you have to leave early?

You can add a question word before ‘do/does’ to form an open question.

Example: When do you have to leave?

Note that ‘must’ is limited to the present* (there’s an exception… keep watching) while ‘have to’ can be used in the past, present and future. To fully grasp this discrepancy, let’s look at their meanings. 

Part 3: Uses 

First, let’s look at ‘must’. It’s usually used to express an obligation, but it holds a wide range of meanings. Here’s a breakdown:

  1. Personal Obligation
    ‘Must’ generally conveys a strong, personal sense of obligation. This is the most common way it’s used. The speaker thinks that the action (the base form following our modal verb) is a personal responsibility.
    • Example: 
    • I must finish my essay today. (My teacher set a deadline for submission and I want to comply) 
    • She must apologize to him. (The speaker believes apologizing to him is her duty)
  2. Rules or Commands
    ‘Must’ can also state official rules or regulations.
    • Example: 
    • You must follow safety guidelines. (It’s a command)
    • Employees must wear badges. (The company made it a rule to follow)
  3. Necessity
    ‘Must’ can express something that is needed. It’s close to an obligation, but it’s more about a requirement for a certain outcome instead of simple duty.
    • Example: 
    • We must book our tickets now. (It’s necessary if we want to go on our trip)
    • You must remember your password. (If you don’t, you will not have access to your bank account, oops!)
  4. Advice
    ‘Must’ can offer strong suggestions.
    • Example: 
    • You must try that new diner. (I like it so much, I’m recommending it to you)
    • The children must visit that exhibit before it closes. (I advise the kids to go to the museum)
  5. Prohibition (Must Not)
    ‘Must not or mustn’t’ strongly forbids an action.
    • Example: 
    • You mustn’t eat in the library. (it’s prohibited) 
    • We must not enter without permission. (this action is not allowed) 
  6. Present Deduction or Certainty
    ‘Must’ can infer a likely conclusion based on evidence. It expresses a logical assumption with a high degree of certainty, at least from the point of view of the speaker.
    • Example: 
    • They must be tired after such a long flight. (I haven’t seen the people I’m picking up at the airport but it’s safe to say they will be tired since they’ve spent a lot of time on a plane)
    • It must be very cold outside. (I haven’t been outside but perhaps I see people coming in wearing warm clothes and the fact that the outdoor temperature has dropped can be considered as a certainty) 
  7. Past Deduction or Certainty
    By now you might have noticed that ‘must’ is usually confined to the present, and you’re not wrong. But here’s an oddity, ‘must’ expresses a past deduction when it’s followed by have and a past participle. It allows you to make a logical conclusion about a past situation.
    • Example: 
    • She must have left already. (The speaker concludes that she left earlier since she’s not home at the moment). 
    • They must have heard the news by now. (Again, the speaker makes an assumption about a past action (hearing the news) thanks to some current information, perhaps everybody knows the news now so it’s a foregone conclusion that they heard it as well)

Now, let’s look at ‘have to’. It’s used to express obligations imposed by external factors or requirements. As opposed to ‘must’ which focuses on personal obligations. Furthermore, unlike “must,” have to can be used in all tenses. Let’s break it down:

  1. External Obligation
    ‘Have to’ indicates a requirement often set by outside circumstances. It’s very similar in meaning to ‘must’ but the obligation is set by others.
    • Example: 
    • I have to complete this report by 5 p.m. (My boss has set this obligation)
    • She has to wear a uniform. (External conditions make this mandatory)
  2. Present or Past Deduction or Certainty
    Just like ‘must’, ‘have to’ can be used to express a deduction or certainty but with a greater emphasis on external factors.
    • Example: 
    • The store is closed; it has to be their day off. (maybe not the greatest deduction, but still the observation of the closed store leads to an assumption about the store’s working days)
    • She had to know the answer. (the speaker assumes she knew the answer and states it almost as a certainty)
  3. Optional Obligation (Don’t Have To)
    ‘Don’t Have to’ is an interesting case. It implies that something is not required. The meaning of the negative form is not close to the negative form of must
    • Example: 
    • You don’t have to come to the meeting. (Attending the meeting is optional, up to you!) 
    • We don’t have to bring any materials. (Come empty-handed and that’s just fine) 
  4. Past and Future Obligations
    Here ‘Have to’ acts as a substitute for “must” in past and future contexts. Must doesn’t have a past or future form. Instead ‘have to’ takes up this responsibility.
    • Example (Past): I had to cancel my appointment. (the obligation to cancel happened in the past)
    • Example (Future): She will have to study hard for the exam. (the obligation to study is going to happen later) 
  5. Annoyance
    ‘Have to’ can express frustration about burdensome actions.
    • Example: 
    • Do they have to talk so loudly? (the loud talking is a source of irritation)
    • He always has to make everything a competition. (his competitiveness is an inconvenience to the speaker)

Part 4: Common mistakes

  1. Using ‘must’ in past and future contexts

Example: I must go to the dentist yesterday. = I had to go to the dentist yesterday. Remember, for past or future, “must” doesn’t work. Use “had to” or “will have to”. 

  1. Mixing up negative forms

Example: You mustn’t attend if you don’t feel like it. = You don’t have to attend if you don’t feel like it. “Mustn’t” means something is not allowed, while “don’t have to” means it’s optional. So, even though many positive sentences can use must and have to interchangeably, when dealing with a negative, be mindful of the meaning. In the example it’s clearly an optional obligation as the clause shows (if you don’t feel like it is highlighted), so only don’t have to fits here. 

  1. Omitting ‘to’ with have

Example: We will have stop for gas on the way. = We will have to stop for gas on the way. Always include the preposition ‘to’ when using ‘have to’ to express an obligation, otherwise it sounds a bit clumsy. 

Wrap up: There you have it! Must and Have To, the former is almost exclusively used in the present while the latter can be used across the past, present and future. You don’t have to watch another of our videos, but we’d appreciate it! 😉 Hopefully, this has been helpful. A link to some free material to practice by yourselves can be found in the description below. Keep practicing, and you’ll get the hang of it. Thank you for watching. Until next time!