Modal and Related Verbs

Unit 6, Lesson 1A - Grammar Reference

Lesson Explanation

1 Obligation and necessity

  • Must: Used when there is no choice, or the obligation comes from the speaker. ("Your friend really must study harder.")
  • Have to / Have got to: Similar to must, but indicates the obligation is from somebody else or an outside rule. ("I had to wear braces.")
  • Need: Used as a main verb. ("He needs to be courageous.")
  • Related verbs: be required to, be obliged to refer to an outside authority.

2 Duty and advice

  • Should / Ought to: Used to give opinion or advice. ("Animals shouldn't suffer.")
  • Related verbs: be supposed to is used to talk about what should happen according to rules or general expectations. ("Animals are not supposed to suffer.")

3 No obligation

  • Don't have to / Needn't: Means "it isn't necessary". ("He doesn't have to work today.")
  • Related verbs: not required to, not obliged to. ("Actors are not obliged to be glamorous.")

4 Ability

  • Can / Could: Describe general ability. ("He could play chess.")
  • Be able to: Used specifically to describe the completion of a specific action in the past. ("He was able to phone.")
  • Related verbs: managed to, succeeded in. ("The police managed to find the child.")

5 Permission & Prohibition

  • Permission: Can / Could ("Can I ask a question?"). Related: allowed, permitted to.
  • Prohibition: Mustn't, Can't, Couldn't ("People can't park here"). Related: not allowed to, forbidden to.

6 Possibility

  • Can: Generally possible. ("It can rain heavily in winter.")
  • Could / Might: A specific thing is possibly true, or an uncertain future intention. ("We might go for a meal.")
  • Related verbs: likely to, bound to (sure to).

Practice Quiz (29 Questions)

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