Can/Could/Be Able To

Have you ever found that even though you can speak English very well, you don’t feel you will ever be able to use every aspect of it correctly? Imagine if you could speak it like a native

Now, here’s a question: what is the difference between ‘can’, ‘could’ and ‘be able to’ in the paragraph above? Not sure?! Read on to find out!

Can

STRUCTURE = can + bare infinitive (can do, can make).
NEGATIVE = cannot/can’t.
Used to express possibility, permission, ability and make informal requests.
Only used in present simple and past simple (could).
For other tenses ‘be able to’ is needed (see below).

FUNCTION	EXAMPLE
Possibility	I can meet you at the restaurant at 7pm.
Permission	You can drive at 70mph on a motorway in the UK.
Ability	He can’t ride a bike.
Informal request	Can you pass me my bag, please?

Could

STRUCTURE = can + bare infinitive (could do, could make).
NEGATIVE = could not/couldn’t.
Used to express possibility, permission, ability and polite requests.
Often used with: see, smell, hear, feel, taste, remember, understand.
The past simple of ‘can’.

FUNCTION	EXAMPLE
Possibility	When I was at school, my teacher told me I could be whatever I wanted to be.
Permission	Our boss said we could finish early as a reward.
Ability	My brother could ride a bike when he was three.
Polite request	Could you get back to me before the end of the day, please?

Be Able To

STRUCTURE = be able to + infinitive (be able to do, be able to make).
NEGATIVE = be + not able to.
Used for different tenses where ‘can’ cannot be used, as well as for polite requests.

TENSE	EXAMPLE
Present Perfect	I have been able to speak three languages since I was a child.
Future	My sister will not be able to swim for weeks due to her broken arm.
Conditional	We should be able to get there at 3pm.
Polite request	Would you be able to post this for me, please?

NOTE: was able to vs. could

⇒ could is used for general ability

My granddad could play the piano.

⇒ be able to is used for a specific situation

I ran after him but I wasn’t able to catch him.

So back to our original question – when you want the salt, do you use ‘can’, ‘could’ or ‘be able to’?

Friends – ‘can’.
More formal settings such as a lunch meeting with your boss, meeting your girlfriend’s parents for the first time – play it safe and go for ‘could’ or ‘be able to’!