Can and Could are special verbs frequently used in English.
They are modal verbs, which means they do not get conjugated like regular verbs, making them easy to use!
Could is the past tense of can. So, they are the same verb but could refers to the past.
How to conjugate can
No matter the subject, can never changes. It doesn’t take an -s at the end. In the past tense, it simply becomes could.
| Personal pronouns | Conjugation of can in the present tense |
|---|---|
| I | can |
| You | can |
| He, she, it | can |
| We | can |
| You | can |
| They | can |
Can is not used alone. It is usually followed by a verb in its base form (infinitive without to). The structure of a sentence with can is: subject + can + base verb + rest of the sentence.
Examples :
| Sentence | Explanation | Audio |
|---|---|---|
| I can swim. | Ability to swim. | |
| You can read. | Ability to read. | |
| He can stay as long as he wants. | Permission to stay without a time limit. | |
| We can have a drink. | Suggestion or possibility to have a drink. | |
| You can be proud of you. | Expression of a reason for feeling pride or satisfaction. | |
| They can watch TV tonight. | Permission or opportunity to watch TV later in the day. |
In the negative form
The negative form is simple: just add not to the end of can: can + not = cannot. The contracted form is commonly used: can + not = can’t.
Examples :
| Sentence | Explanation | Audio |
|---|---|---|
| I can’t stand children. | Expresses a strong dislike for children. | |
| You cannot talk to me like that! | Emphasizes a strong disapproval of the way someone is speaking. |
To ask a question
When asking a question with can, we don’t use the auxiliary verb do. Instead, can is placed at the beginning of the sentence, followed by the subject: can + subject + verb …?
| Example sentence | Explanation | Audio |
|---|---|---|
| Can you help me? | Asking if someone is able to assist. | |
| Can you smell that? | Asking if someone can perceive an odor or scent. |
Pay Attention to the Response
When someone asks you a question starting with can, you should use can in your reply!
| Example sentence | Explanation | Audio |
|---|---|---|
| Can you close the door please? | A polite question asking if a person is able to or willing to close the door. | |
| Yes, I can / No, I can’t. | Simple affirmative or negative response. In English, we don’t say “Yes, I can do it” or “No, I can’t do it.” |
This response format is essential and applies to all modal verbs: do, must, could, should, etc.
When to use can
As you’ve seen, can is generally translated as “to be able to” or “to be allowed” in English.
However, the usage of can is more nuanced, and it has several other uses that will be explained here.
Expressing Ability
Can expresses physical capacity, meaning the ability or the sense of being able to do something.
| Example sentence | Explanation | Audio |
|---|---|---|
| He can swim for hours. | Indicates the physical ability | |
| Can you run with me? | Asking if someone has the ability to run alongside. | |
| Can you lift my suitcase, please? | Asking if someone is physically able to lift the suitcase |
Expressing Know-How
Can also expresses intellectual ability, meaning the knowledge or skill to do something. In English, this is often translated as power to do something. In such cases, using to be able to is also possible.
| Example sentence | Explantion | Audio |
|---|---|---|
| He can read. | Indicates that he knows how to read, showing intellectual ability. | |
| He is able to read, he’s 6. | Indicates that he has acquired the skill of reading, suitable for his age. | |
| I can play the guitar. | Indicates the ability or skill to play a musical instrument. | |
| Can you speak English? | Asking if someone has the knowledge to communicate in English. |
Permission
Can is used to ask for or give permission.
It is the most common polite way to request authorization.
| Example sentence | Explanation | Audio |
|---|---|---|
| Can I help you? | Politely asking if you are allowed to offer assistance. | |
| He can go to the movies tonight. | Giving permission to go to the cinema. | |
| Can we use your phone? | Asking for permission to use someone’s phone. |
Note: May is a more formal and refined way to ask for permission instead of can.
| Example sentence | Explanation | Audio |
|---|---|---|
| May I help you, my dear? | A very polite and formal way of offering assistance. |
Possibility
Can is also used to express possibility, which translates as: it is possible that.
| Example sentence | Explanation | Audio |
|---|---|---|
| He can come whenever he wants. | Indicates the freedom to come at any time. | |
| The traffic can get really bad in Paris. | Expresses that it’s possible for the traffic to become very heavy. | |
| People can sometimes be awful. | Means that it is possible for people to behave badly at times. |
With a perception verb (a sensation)
Perception verbs describe sensations from our senses: sight, touch, smell, etc.
In English, we always use can before these perception verbs. However, when translating into other languages, you don’t always translate can.
| Perception Verb | Example sentence | Audio |
|---|---|---|
| To see (= to perceive visually) | Can you see the apples in the tree? No, I can’t see any. | |
| To hear (= to perceive sound) | I can hear you even if you can’t see me! | |
| To feel (= to perceive physically or emotionally) | I can feel you are trembling. | |
| To smell (= to perceive an odor) | I can smell chocolate! Someone’s eating a piece of cake! | |
| To taste (= to perceive flavor) | I can taste strawberry in this cake. |
Expressing a prohibition: can’t or cannot
To express a prohibition, several formulas can be used, including can’t or cannot.
| Example sentence | Explanation | Audio |
|---|---|---|
| Sorry, you can’t go this way. | Indicates that going that way is not allowed or is forbidden. | |
| You cannot smoke here. | States that smoking is not permitted in that location. |
Expressing impossibility
If someone tells you something that seems completely unrealistic or impossible, you use can’t to express disbelief.
| Example sentence | Explanation | Audio |
|---|---|---|
| I can’t believe you, it can’t be true! | Expressing disbelief about something or someone. |
How to conjugate could
Just like can, could does not change form. It always stays the same.
Could is the past tense form of can.
In the negative form
Again, it’s very simple, just add not: could + not = could not. The contracted form is commonly used: could + not = couldn’t.
To ask a question
To ask a question with could, place could at the beginning of the sentence, followed by the subject: could + subject + verb…?
When to use could
| Usage | Example sentence | Explanation | Audio |
|---|---|---|---|
| Past form of can | I could run fast when I was young. | Describes an ability you had in the past. | |
| Politely asking for something | Could you tell me where is the post office, please? | A polite way of requesting information or help. | |
| Making a suggestion | You could walk the dog. | Suggesting an action in a friendly manner. | |
| Expressing a mild reproach | You could help me sometimes! | Pointing out that someone could be more helpful (slightly critical). |
What is the difference between can and could
The main difference between can and could is the tense: can is used for the present, while could is mainly used for the past tense.
A second important difference is the level of politeness: could is more polite than can.
Do not use will with can to express the future
Will is a modal verb used to express the future. Since can is also a modal, they cannot be used together to form the future tense.
If you want to express an ability or skill in the future, use the structure: subject + will + to be able to + verb + rest of the sentence.
Example :
| Tense | Example sentence | Explanation | Audio |
|---|---|---|---|
| Present | He can swim. | Indicates a current ability to swim.. | |
| Future | He will be able to swim soon. | Expresses the ability to swim in the near future. |
