Main Difference – Can vs. Could
A modal verb is an auxiliary verb that expresses necessity or possibility. Can and could are two modal verbs that express possibility and ability. The main difference between can and could is that could is the past form of can.
Can vs. Could– Meaning and Usage
Can and could are two modal verbs that can be used to indicate possibility, ability, permission, and requests. As mentioned above, could is the past form of can. However, there can be a difference in meaning of these two verbs, apart from the obvious disparity in time. Both these verbs can be used to indicate
Possibility
We can use can to express a general statement or a known fact that is possible.
It can be dangerous to walk alone on this path.
You can use this spray as a mosquito repellant.
If we replace can with could in the above examples, you’ll notice that could only express a weak possibility. There is a hint of uncertainty if we use could in these examples.
It could be dangerous to walk alone on this path.
If we want to indicate that something was possible in the past, you can use could.
They could have finished this days ago.
They knew that it could only be a lie.
Ability
We can use can to talk about an individual’s skills and abilities. Can is also used to indicate an ability to do something.
You can obtain the receipt from the counter.
She can speak Spanish, French and Russian.
This little boy can swim like a fish.
You can make a lot of money from this job.
Could is used to talk about an ability in the past.
When she was young, she could climb any mountain.
He couldn’t walk before the operation.
He can swim like a fish.
Permission
Can is used to ask and give permission for something.
Can I go home now?
Yes, you can go home now.
Could is more formal than can, when it comes to asking for permission. In addition, it is important to remember that could cannot be used to give permission. Compare the sentence pairs below.
Can I ask you a question? – informal
Could I ask you a question? – formal
Can I get you something to eat? – informal
Could I get you something to eat? – formal
Requests
We can use both can and could to make requests. Could is more formal than can in this situation as well.
Can I borrow your pen?
Could I borrow your pen?
Difference Between Can and Could
Tense
Can is generally used in the present tense.
Could is the past form of can.
Possibility
Can indicates a stronger possibility.
Could indicates a weaker possibility.
Ability
Can indicate an ability, skill possessed by an individual.
Could indicate an ability, skill in the past.
Permission
Can is used to ask and give permission.
Could is only used to ask for permission.
Formality
Can is not as formal as could when used in requests.
Could is more formal than can when used in requests.
