"Are one case" does not have a direct antonym as it is a phrase that describes a singular instance or situation. However, some possible antonyms for "case" could include "multiple cases," "different cases," or "opposite cases." In terms of the verb "are," which indicates a state of being, some antonyms could be "aren't," "isn't," or "wasn't." It's important to note that antonyms for specific phrases may not always exist, as they are often context-dependent and can vary depending on the situation or context in which they are used.