The phrase "is on a par" can be substituted with different synonyms based on the context of the sentence. Some of the common synonyms are "equals", "matches", "compares", "rivals", "challenges", "competes", "corresponds" and "aligns with". For example, "Her performance is on a par with her colleagues" can be rewritten as "Her performance equals that of her colleagues", "Her performance matches the level of her colleagues" or "Her performance rivals that of her colleagues". Similarly, "The company's revenue is on a par with its competitors" can be replaced with "The company's revenue compares with its competitors" or "The company's revenue aligns with that of its competitors".