Modal verbs

<aside> 💡 It's common for English language learners to overuse certain modals (e.g., can, etc.) and certain modals can unintentionally lead to over hedging (See Boosting and the nuances of hedging).

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Modal verbs are auxiliary verbs that express necessity, possibility, permission, ability, probability, or obligation. In English, the primary modal verbs are:

1. Can / Could:
   • Use for Ability: "She can speak four languages."
   • Possibility: "It could rain today."
   • Request or Permission (especially Could): "Could I borrow your book?"
2. May / Might:
   • Permission (more formal than Can): "May I leave the room?"
   • Possibility or Probability: "She might come to the party."
3. Will / Would:
   • Future Actions (Will): "I will go to the store later."
   • Polite Requests or Offers (Would): "Would you like some coffee?"
   • Hypothetical Situations (Would): "I would travel more if I had more time."
4. Shall:
   • Formal Suggestion or Offer (mainly British English): "Shall we dance?"
   • Future Actions (formal): "Shall I open the window?"
5. Should / Ought to:
   • Advice or Recommendation: "You should see a doctor."
   • Expectation: "He ought to be here by now."
6. Must:
   • Obligation or Necessity: "You must stop at a red light."
   • Strong Recommendation: "You must visit the new museum."
   • Logical Assumption: "He must be tired after the long journey."
7. Dare:
   • Challenge or Bravery (less common): "Dare she speak out?"
8. Need (Semi-modal):
   • Necessity (in questions and negatives): "Need I say more?"
9. Used to:
   • Past Habit or State (not a modal in the traditional sense, but functions similarly): "I used to play basketball."

Usage Guidelines

• Modals do not change form according to the subject. For example, "She can," "They can."
• After a modal verb, the base form of the verb is used: "She can speak," not "She can speaks."
• Modals do not have all tense forms, such as past or future. Some have past forms (like "Could" as the past of "Can") or use other modals for different tenses.
• Negative forms are made by adding "not" after the modal: "She cannot (can't) speak French."

Important Points

• The use of some modals can vary in formality. For example, "Shall" and "May" are more formal.
• The choice of modal can subtly change the meaning of a sentence, especially in terms of politeness, certainty, and formality.