Can / Could
Use can for present ability, permission, and possibility ("I can swim"); use could for past general ability and for more polite requests and guesses ("She could read at four", "Could you help me?").
Formula
Examples
Usage
- •Can: present ability, permission, or possibility
- •Could: past ability, polite requests, or weaker possibility
- •Could: more polite than "can" for requests
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Can talks about the present: ability ("I can swim"), permission ("Can I use your phone?"), and general possibility ("It can be cold in April"). Could is the past form of can for general ability ("She could read when she was four") and a more polite, softer version for requests and possibility in the present.
Neither can nor could is ever followed by "to" — the next verb stays in its base form: "I can swim", not "I can to swim".
How polite are can, could, and would?
"Could" is more polite than "can" for requests: "Could you help me, please?" sounds softer and more formal than "Can you help me?" — both are correct, but could is the safer choice with people you don't know well.
For a single, specific past success (not general ability), English prefers "was/were able to" or "managed to" instead of could: "I was able to open the door" describes one occasion, while "I could open the door [when I was younger]" describes an ongoing ability.
Comparison Table
| Form | Present | Past / more polite | Example |
|---|---|---|---|
| Ability | can (now) | could (general, past) | I can swim. / She could read at four. |
| Permission | can (informal) | could (more polite) | Can I sit here? / Could I sit here? |
| Request | can (direct) | could (softer, more formal) | Can you help? / Could you help, please? |
| Possibility | can (general truth) | could (weaker, less certain) | It can be cold. / It could rain later. |
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When to Use Can / Could
Present ability
I can run 10 km without stopping.
Past general ability
She could read when she was four.
Polite request or guess
Could you pass me the salt, please?
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More Examples
I can run 10 km without stopping.
What you can do now
She could read when she was four.
What you could do before
Could you pass me the salt, please?
A polite way to ask for something
It could rain tomorrow.
Something that might happen, you are not sure
Can I use your phone?
Asking for permission
Common Mistakes
- ✗"Can" never takes "to": "I can to swim" is wrong — use "I can swim".
- ✗Don't use "could" for a single specific past event: say "I managed to open the door" not "I could open the door" in that context.
Tips
- ✓"Could" is the past tense of "can" and also a polite alternative in requests.
- ✓For ability in the past (success on one occasion), use "was/were able to" instead of "could".
Advanced Notes
The "could for single past achievement" trap is one of the subtlest modal errors: "could" implies general past ability, not a specific success. "I could finally open the jar" sounds odd to native ears — "I managed to open it" or "I was able to open it" is correct. In requests, "could" is more tentative than "can" and significantly more tentative than "would" — the hierarchy "can < could < would" reflects increasing formality and politeness. "Can't" also functions as logical deduction: "She can't be at home — I just saw her leave."
FAQ
Why is "I can to swim" wrong?
Can (like could) is a modal verb and is never followed by "to" — the next verb goes straight into its base form. The correct sentence is "I can swim."
Why is "I could open the door" sometimes wrong?
Could describes general past ability, not a single specific achievement. For one particular past success, use "was/were able to" or "managed to": "I managed to open the door," not "I could open the door," when talking about that one occasion.
Can vs could — which is more polite?
Could is more polite and more formal than can, especially for requests: "Could you pass the salt?" is softer than "Can you pass the salt?" Both are grammatically correct — could is just the gentler choice.
What is the difference between can and could?
Can is present tense: current ability, permission, or possibility. Could is either the past tense of can (past general ability) or a more polite/tentative version of can used in the present for requests and guesses.
Can "can't" mean something is impossible, not just "not allowed"?
Yes — "can't" also expresses logical deduction, meaning something is almost certainly not true: "She can't be at home — I just saw her leave." This is different from "can't" meaning lack of ability or permission.
Practice
- 1.I speak three languages.
- 2.When I was a child, I climb trees very fast.
- 3. you help me with this bag, please?
- 4.I swim — no "to" needed.
- 5.Yesterday, after a lot of effort, I finally open the jar.
Compare With
Other A2 Topics
Present Continuous
Used for actions happening now or temporary situations
Past Continuous
Used for interrupted past actions or background description
Future with Going to
Used for decided plans and evidence-based predictions
Comparatives and Superlatives
Used for comparing qualities between items or identifying the extreme
Prepositions of Time and Place
Used for time and location relationships using in, on, at
Adverbs of Frequency
Used for stating how often something happens
Possessive 's
Used for showing ownership or association using apostrophe + s
Quantifiers: Some, Any, Much, Many, A Lot Of
Used for unspecified quantities in positive, negative, and question contexts
Basic Linkers: And, But, Or, Because, So
Used for connecting ideas within or between sentences
Object Pronouns: Me, You, Him, Her, It, Us, Them
Used for replacing nouns as the object of a verb or preposition
Countable and Uncountable Nouns
Countable nouns can be counted (a book, two books); uncountable nouns cannot (water, money).
Too and Enough
Say when something is more than needed (too) or exactly enough (enough).
Adverbs of Manner
Adverbs of manner describe how an action happens.