The word can is a modal verb and an auxiliary verb that is used to help express ability, possibility, permission, doubt, or to make requests and offers.
Here are the 7 most important rules of can so you can start using it like a pro!
1. used for all subjects and pronouns
Same for all subjects. “I can”, “She can”, “You can”, “We can”, “They can” or “John can”.
2. Use the Bare Infinitive
The verb after can must be in the bare infinitive without using the word “to”.
- He can play golf.
- He can to play golf. X (no “to”)
- He can played golf. X (no -ed)
- He can plays golf. X (no -s)
- Usually the infinitive is when the base verb is used with “to” before it: He is able to play golf. She wants to eat at 8 o’clock. (In these examples “play” and “eat” are the bare infinitives)
3. Never conjugated
Can is never conjugated. This means it cannot change its form. E.g. The auxiliary verb “be” can conjugate to am, are, is, was, or were.
4. used to help the main verb
Can is a helping verb or auxiliary verb which means it expresses which tense or mood and can form a question or negative sentence for the main verb is being used.
| Sentence | Description |
|---|---|
| “I play football.” | A statement about an action they do. |
| “Can I play football?” | Using can at the beginning creates a question for permission to do the action. |
| “I speak English.” | A statement about an action they do. |
| “I can speak English.” | Using can to express their ability to do the action. |
| “I cannot speak Japanese.” | Using can/ cannot to express they do not have the ability to do the action. It negates the main verb “speak.” |
5. Only use one modal verb per sentence
It is grammatically incorrect for can and can’t to be used before or after another modal verb: “I can might…” / “We should can…” / “Can you will…”. It is possible to substitute can for “be able (to),” to complete the sentence correctly “I might be able to…” / “We should be able to…”
- She may can help you with your homework. (Incorrect)
- She may be able to help you with your homework. (Correct)
6. used in the present Tense
Can is used in the present tense. The past tense of can is could.
There is no correct form for can in the future tense but we can use can with the indication of the future for the same result, eg., “I can go tomorrow”, here I can go remain the same and tomorrow is the indication of the time in the future.
OR
Substitute can for “will be able to” which has the same meaning.
- Present: “I can solve complex math problems quickly.”
- Past: “When I was a child, I could climb trees easily.”
- Future 1: “She can drive once she gets her license next month.”
- Future 2: “She will be able to drive once she gets her license next month.”
7. No infinitive or participles
No infinitives or participles. This means can is not used with “to,” “-ing,” or “-ed.”
Exercises & Worksheet Quiz (Answers below)
| Sentence | Correct ✓ | Incorrect X |
|---|---|---|
| He can plays football? | ||
| She can speak four languages. | ||
| It can get very hot in July. | ||
| Can I used your phone? | ||
| Can he cooked? | ||
| You can go as soon as you’re ready. | ||
| I can helps you with that. | ||
| Can you close the window? | ||
| They can finish the project by tomorrow. | ||
| Can it really be true? | ||
| Can should you please lower the volume? | ||
| We can travel to Japan next year. | ||
| Can will that small car carry all of us? | ||
| Can this old computer still run modern software? | ||
| They can solves complex puzzles quickly. | ||
| Can you stopped drinking coffee late at night? | ||
| You can choose from over ten flavours of ice cream. | ||
| She can read before she started school. | ||
| Can come she to our party tomorrow? | ||
| You can finish your homework after dinner. |
Answers
| Sentence | Correct ✓ | Incorrect X | Notes |
|---|---|---|---|
| He can plays football? | X | Incorrect verb form; should be “play”. | |
| She can speak four languages. | ✓ | Correct as stated. | |
| It can get very hot in July. | ✓ | Correct as stated. | |
| Can I used your phone? | X | Incorrect verb form; should be “use”. | |
| Can he cooked? | X | Incorrect verb form; should be “cook”. | |
| You can go as soon as you’re ready. | ✓ | Correct as stated. | |
| I can helps you with that. | X | Incorrect verb form; should be “help”. | |
| Can you close the window? | ✓ | Correct as stated. | |
| They can finish the project by tomorrow. | ✓ | Correct as stated. | |
| Can it really be true? | ✓ | Correct as stated. | |
| Can should you please lower the volume? | X | Incorrect modal usage; “Can you please” is correct. | |
| We can travel to Japan next year. | ✓ | Correct as stated. | |
| Can will that small car carry all of us? | X | Incorrect modal usage; “Can that small car” is correct. | |
| Can this old computer still run modern software? | ✓ | Correct as stated. | |
| They can solves complex puzzles quickly. | X | Incorrect verb form; should be “solve”. | |
| Can you stopped drinking coffee late at night? | X | Incorrect verb form; should be “stop”. | |
| You can choose from over ten flavours of ice cream. | ✓ | Correct as stated. | |
| She can read before she started school. | X | Incorrect tense; should be “could”. | |
| Can come she to our party tomorrow? | X | Incorrect structure; should be “Can she come to our party tomorrow?” | |
| You can finish your homework after dinner. | ✓ | Correct as stated. |
Author Bio
