[Grammar] modals of ability, past and present

[Iryn_]

Hello, everybody!
Would you be so kind to check my understanding of the topic? I've read lots of articles on different websites, but I want to make sure I have structurized all that information right.

General ability in the preset: can/can't; am/is/are (not) able to
Specific action in the present: can/can't

Gen.ability in the past: could/couldn't, was/were (not) able to
Spec.action in the past: could (but only with see, hear, feel, smell, taste, remember, believe, understand, decide), couldn't, was/were (not) able to, managed to/didn't manage to.

 

[J&K Tutoring]

Could is not specific to the past. It also works in the future.

 

[Matthew Wai]

'He could be the next CEO' refers to a future possibility.