There are several synonyms for the phrase "be able to." Some of the most common include have the ability to, have the capacity to, have the power to, be capable of, be competent to, and be proficient at. These phrases all indicate a similar meaning, which is the ability to perform a certain task or achieve a certain goal. Other less common synonyms include be up to, be equal to, and be in a position to. No matter which synonym is used, the idea conveyed is one of capability and competence. By using these variations in language, writers can add variety and clarity to their writing.