Related Clues:

• Auxiliary, e.g.
• Heads or tails, e.g.
• "Give" or "take," e.g.
• Predicate necessity
• 'Adjective' or 'adverb,' e.g.
• Plus or minus
• Subject, often
• Morning or evening, e.g.
• Pen or pencil, e.g.
• "Trick" or "treat"
• Fly or drive
• Sink or swim, perhaps
• Pluralizable word
• What an adjective modifies
• Proper word