(third-person singular simple present being able to, present participle was able to, simple past and past participle been able to)
- See be for the full inflection of be.
- To be able to may be used whenever can (the modal verb) is used; it is always used in tenses where can, which is defective, has no corresponding form. For example, "He said I would be able to go" is the same as "He said I could go", and "You will be able to watch" replaces the non-existent *You will can watch.
- To be able to can be used instead of could to avoid ambiguity between would be able to and was/were able to. For example, "I know I could win" can mean either "I know I was able to win" or "I know I would be able to win", whereas the forms using to be able to avoid this ambiguity.