Modal Verbs (can, must, should...)
🎯 Learning Goals
- Understand how modal verbs change the meaning or 'mood' of a sentence.
- Learn the grammatical rules for using modals (no '-s', followed by base verb).
💡 Why Learn This?
Modals are the 'attitude' words of English. Without them, you can only state raw facts like 'I swim'. Modals let you express ability ('I can swim'), obligation ('I must swim'), or advice ('I should swim').
Modifying the Main Verb
A modal verb is a helper verb that expresses necessity or possibility. Unlike normal verbs, modals don't change their form (they never take an '-s' or '-ed') and are always followed directly by the base form of a main verb without 'to'.
Common Modal Categories
- ・ Ability / Permission: can, could (e.g., 'You can go now.')
- ・ Advice / Recommendation: should (e.g., 'You should sleep.')
- ・ Obligation / Certainty: must, will (e.g., 'You must stop.')
⚠️ Common Pitfalls
A very common mistake is adding 'to' after a modal verb (e.g., 'I must to go'). This is incorrect! Always use the bare infinitive: 'I must go'. Another trap is trying to add '-s' for he/she/it: 'He cans swim' is wrong; it's simply 'He can swim'.
Attitude Simulator
Change the modal verb to see how the meaning of 'I [modal] study' changes.
📝 Summary & Recap
- Modals add meaning like ability, obligation, or advice to the main verb.
- Rule #1: Modals never change form (no '-s', '-ed', or '-ing').
- Rule #2: The main verb after a modal is always in its base form (no 'to').
Quick Drill
Test your understanding of modal verbs!
🔍 Deep Dive (Optional)
Fun fact: 'Will' and 'Would' are also modal verbs! This means the future tense in English ('I will go') is actually just using a modal verb to express certainty about a future event.