Use of Can and Could

"Can" expresses present ability, a strong possibility, or informal permission, while "could" indicates past ability, a weaker possibility, or a more formal and polite request. Both verbs can be used for ability, possibility, and permission, but "could" adds a layer of formality, uncertainty, or a past tense perspective. 

Uses of Can

• Present Ability: 

  To state that someone or something is capable of doing something now. 

  • Example: "I can speak three languages". 
Strong Possibility: 
To suggest that something is very likely to happen. 
Example: "A scorpion's sting can cause intense pain". 
Informal Permission: 
To give or ask for permission in a casual way. 
Example: "Can I use your phone?". 

Uses of Could

Past Ability: 
To describe a general ability in the past. 
Example: "When I was younger, I could run for miles". 
Weak Possibility: 
To express that something might happen, but it's not certain. 
Example: "It could rain later today". 
Formal/Polite Requests: 
To make polite requests, more formal than using "can". 
Example: "Could you please help me?". 
Deduction: 
To make a deduction about a current situation. 
Example: "That noise could be the wind".