Historical clue formulations

• Give ___ (mind) — 2015-03-21
• Keep one's ___ the ground — 2013-10-20
• Keep one's ___ the ground — 2012-02-20
• Keep an ___ the ground — 2007-02-05
• Keep an ___ the ground — 2007-01-07
• Keep an ___ the ground — 2006-07-20
• Have an ___ the ground — 2005-10-30
• Keep an ___ the ground — 2005-05-12
• Give ___ (heed) — 2001-07-19
• Keep an ___ the ground — 2001-04-12
• Keep an ___ the ground — 1998-04-19
• Keep an ___ the ground — 1998-02-25
• Keep one's ____ the ground — 1995-07-19
• _____ the ground — 1994-04-03