#EngClass: Modal verb – Must

To continue our discussion on modal verb, this time, we’ll talk about “must”. “Must” is commonly used to express:

  • personal obligation,
  • necessity,
  • strong recommendation,
  • certainty.

Instead of “must”, native speakers from America usually prefer the more flexible form “have to”.

 

When to use “must”?

People generally use “must” to express personal obligation, something that the speaker thinks is necessary. Other than that, “must” is also used for the following purposes:

slide7

  1. To express obligation or duty.
    • Example:
      • You must wear a seat belt at all times.
  2. To emphasize the necessity of something.
    • Example:
      • You must give up smoking. It’s bad for you.
  3. To say that you’re sure that something is true.
    • Example:
      • It must be cold outside. It’s raining hard.
  4. To express positive logical assumptions.
    • Example:
      • She must have been at home. Her lights were on.
  5. To make a strong recommendation.
    • Example:
      • The ice cream here is delicious. You must try some.

 

How to use “must”?

slide8

  • Like every other modal verbs, “must” is followed by a main verb.
  • And to form a negative sentence, “not” is placed after the word “must”, before the main verb. It expresses prohibition.
  • “Must” is generally not used in interrogative sentences. For questions, it is more common to use “have to”.

 

  1. “Must” in expressing obligation or duty.
    • Example:
      • You must wear a seat belt at all times.
      • She must cook dinner every evening.
  2. “Must” in emphasizing the necessity of something.
    • Example:
      • You must give up smoking. It’s bad for you.
      • You must study the last two chapters before the test.
  3. “Must” in saying that you’re sure that something is true.
    • Example:
      • It must be cold outside. It’s raining hard.
      • She must be home. The lights are on.
  4. “Must” in expressing positive logical assumptions.
    • Example:
      • She must have been at home. Her lights were on.
      • There’s a missed call on my phone. He must have called last night.
  5. “Must” in making a strong recommendation.
    • Example:
      • The ice cream here is delicious. You must try some.
      • We really must get together for dinner sometime.

 

Present certainty and deduction

“Must” can also be used when you’re certain that something is true, based on evidence. In order to express present certainty, “must” is followed by “be” and a noun or an adjective.

S + must be + noun/adjective/v-ing/prepositional phrase.

Example:

  • She must be a teacher. She’s so wise. (noun: a teacher)
  • She must be cold. She’s shivering. (adjective: cold)
  • She must be singing. I can hear her voice. (present participle: singing)
  • She must be at her friend’s. Nobody is answering the door. (prepositional phrase: at her friend’s)

 

Logical assumptions and past certainty

“Must” is also used in expressing logical assumptions. To express logical assumptions, “must” is followed by “have” and “past participle”.

S + must have + V3

Example:

  • This must have been the book she was talking about. There is no other book with a red cover.
  • She must have won the lottery. She suddenly got a brand new car.

 

Compiled and written by @miss_qiak for @EnglishTips4U on Wednesday, January 25, 2017


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3 responses to “#EngClass: Modal verb – Must

  1. Pingback: #EngClass: Modal verb – Can | @EnglishTips4U·

  2. Pingback: #EngClass: Modal auxiliary | @EnglishTips4U·

  3. Pingback: #EngClass: Would | @EnglishTips4U·

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