• "Can" is used to express general ability in the present or to ask for permission.
Examples:
- "I can swim." (general ability)
- "Can I use your phone?" (permission)
• "Be able to" is used:
When referring to ability in different tenses (past, future, perfect).
When "can" cannot be grammatically used (e.g., after modal verbs or in infinitive forms).
Examples:
- "She was able to solve the problem." (past ability)
- "He will be able to join us tomorrow." (future ability)
- "I’d like to be able to speak Spanish fluently. " (infinitive)
• Key Difference:
Use "can" for simple present or asking permission.
Use "be able to" for flexibility in tense or for more formal/complex constructions.