Does any proposition have both a contrary and a subcontrary?

Question

Quizplus · Accepted Answer

In traditional logic, propositions are categorized into universal affirmatives (A), universal negatives (E), particular affirmatives (I), and particular negatives (O). Contraries are between universal propositions (A and E), where both cannot be true but can be false. Subcontraries are between particular propositions (I and O), where both cannot be false but can be true. Thus, a proposition cannot have both a contrary and a subcontrary because they belong to different categories of propositions.

Does Any Proposition Have Both a Contrary and a Subcontrary