RULE#2 => TO BE ABLE TO is used in all tenses or with the infinitive.
|RULE#1||We use TO BE ABLE TO when we are talking about what happened in a particular situation.||I lost my mobile a few days ago, but I was able to find it.|
|RULE#2||TO BE ABLE TO is used in all tenses or with the infinitive.
CAN has only two forms. (present + past)
|She hasn't been able to eat lately.
He'd like to be able to play the guitar.
|RULE#3||Sometimes TO BE ABLE TO is possible instead of CAN/COULD||I'm able to dance = I can dance.|
|RULE#4||We use CAN/COULD with: UNDERSTAND, FEEL, SEE, HEAR, TASTE, SMELL, REMEMBER||I can smell something burning!
She could hear an owl last night.
|RULE#5||COULD is used for general ability in the past(1) or to show that something is or might be possible(2)||She could speak fluent Spanish when she was 4.(1)
I could do it now, if you like.(2)