Modal Verbs
Modal verbs are special helping words. They come before another verb to tell us about what someone can do, what someone may do, what someone must do, or what someone should do.
What You'll Learn
- How to choose the right modal verb -- can, cannot, may, must, or should -- in different sentences
- How to tell the difference between ability, permission, rules, and advice
- How modal verbs are always followed by the base form of a verb (no -s, no -ing, no -ed)
When to Use
- Talking about ability -- what someone can or cannot do: "She can swim very well."
- Asking for or giving permission: "May I go to the toilet, please?"
- Talking about rules -- what someone must do: "You must wear your school uniform."
- Giving advice -- what someone should do: "You should drink more water."
How to Form
A modal verb always comes before the base form of the main verb. The main verb does not change.
| Pattern | Example |
|---|---|
| Subject + modal + base verb | I can ride a bicycle. |
| Subject + modal + not + base verb | He cannot run in the classroom. |
| Modal + subject + base verb? | May I borrow your eraser? |
Which Modal to Use
| Modal | What It Tells Us | Example |
|---|---|---|
| can | Ability | He can read this book. |
| cannot | No ability | She cannot reach the top shelf. |
| may | Permission | You may eat your snack now. |
| must | Rule / duty | We must keep the classroom clean. |
| should | Advice | You should brush your teeth every day. |
Key Rules
- Use the base verb after a modal: Always say "He can swim." Do not say "He can swims" or "He can swimming."
- No "-s" on the modal: Say "She can paint." Do not say "She cans paint." Modal verbs never change form.
- "Cannot" is one word: Write cannot (one word), not "can not" (two words). The short form is can't.
- "May" is for polite permission: When asking your teacher, say "May I go out?" This is more polite than "Can I go out?"
Common Mistakes
| Wrong | Right | Why |
|---|---|---|
| She can swims fast. | She can swim fast. | Use the base verb after a modal -- no "-s" |
| He must to finish his food. | He must finish his food. | No "to" between the modal and the verb |
| I should eating my vegetables. | I should eat my vegetables. | Use the base verb after a modal -- no "-ing" |
| Can I go to the toilet? | May I go to the toilet? | Use "may" for polite permission in school and exams |
Clue Words
Ability (can / cannot)
able to, know how to, good at
Permission (may)
allowed to, permitted, please
Rules (must)
have to, need to, always, every day
Advice (should)
better, wise, good idea, remember to
Tip: Ask yourself -- is the sentence about what someone can do, what someone is allowed to do, what someone has to do, or what someone is advised to do? This helps you pick the right modal.
Practice Tips
- Label the meaning: Before choosing a modal, decide if the sentence is about ability, permission, a rule, or advice. Then pick the matching modal.
- Base verb check: After you choose a modal, look at the main verb. Make sure it has no "-s", "-ing", or "-ed" ending.
- Polite permission test: If someone is asking for permission, especially from a teacher or an adult, "may" is the best choice.
Quick Reference
| Modal | Meaning | Positive Example | Negative Example |
|---|---|---|---|
| can | Ability | I can tie my shoelaces. | I cannot carry this heavy bag. |
| may | Permission | You may play outside now. | You may not touch the display. |
| must | Rule | We must line up before assembly. | We must not run in the corridor. |
| should | Advice | You should pack your bag early. | You should not stay up too late. |