Can't is often used when we think that something is impossible at the present moment.
When is "could" used?
Could" is a modal verb used to express possibility or past ability as well as to make suggestions and requests. "Could" is also commonly used in conditional sentences as the conditional form of "can."
In statements, we use "can't" for present tense, and "couldn't" for past tense.
What is the difference between "can" and "could"?
When is "can" used?
When is "couldn't" used?
'Can' is a modal verb, which is used with the main verb to express the ability of a person or thing in doing something. On the other extreme, 'could' is the past participle or second form of the verb, which is used with the main verb to talk about a past the ability of an individual in doing something.
It can be used to express ability or opportunity, to request or offer permission, and to show possibility or impossibility.
When is "can't" used?