Related Clues:

• __-to
• See 24
• See 16
• By what means?
• Question not asked in this puzzle's theme words
• Know-__
• -- -to book
• Know-___
• "How come?"
• First word of 'Blowin' in the Wind'
• 'Can you explain this?'
• 'Explain'
• Trainee's question
• By which means
• Do-it-yourselfer's concern