Historical clue formulations

• Spoke monotonously — 2023-11-26
• Spoke tediously, with "on" — 2018-01-14
• Spoke so as to put people to sleep — 2007-02-26
• Went on and on and ... — 2003-11-30
• Used no inflection, maybe — 2001-02-03
• Wasn't colorful — 2000-04-15