What is the Difference Between Can/Could and Be Able To?

The main difference between "can" and "could" lies in their usage and the level of certainty they convey. Both are modal verbs that refer to possibility, ability, or capacity, but they are used in different contexts:

1. Can:

• Refers to a general truth or something that has a strong sense of possibility.
• Used to describe an ability or permission in the present tense.
• Implies that something is very likely to happen.
• Considered more casual when asking for permission.
• Examples: "I can open that door for you," "You can damage your car's engine if you drive around with low motor oil," "Can I be excused?".

1. Could:

• Refers to something that has a weak possibility or might happen, but is not necessarily a general truth.
• Used in the past tense to describe an ability or permission.
• Implies that something might happen, but there's still a possibility it won't.
• Considered more formal when asking for permission.
• Examples: "Mario could have gone to any college he wanted, but he chose UConn because that's where his dad went," "I could win the Chicago Marathon if I train hard enough," "Could you have someone carry my bag upstairs?".

As for "be able to," it is a synonymous expression that can be used interchangeably with "can" and "could" to express possibility, ability, or capacity. However, it is considered more formal and less common in everyday speech.

Comparative Table: Can/Could vs Be Able To

Here is a table comparing the differences between "can," "could," and "be able to":

• Can: This modal auxiliary verb is used to talk about possibility, ability, and permission in the present context. It is more informal than "be able to" and is often used in everyday conversations among friends and family.

• Could: This modal auxiliary verb is used to talk about ability in the present with a special meaning, indicating that someone has the ability to do something but doesn't actually do it. It is also used to talk about past possibility or ability.

• Be Able To: This combination of the main verb "be" and the infinitive "to" is used to talk about ability and possibility in the past, present, and future. It is more formal than "can" and is suitable for both informal and formal conversations.

In summary, "can" is used to talk about present ability and possibility in an informal context, "could" is used to talk about present ability with a special meaning and past ability, and "be able to" is used to talk about ability and possibility across different time frames in a more formal manner.