1.   how   low   cow   now   Hint Half-n-half Clue   2.   Mars   Earth   Pluto   Moon   Half-n-half Clue   3.   aluminum   iron   carbon   copper   Half-n-half Clue   4.   December   January   November   August   Half-n-half Clue   5.   guitar   bugle   flute   trumpet   Half-n-half Clue   6.   31st June 1999   31st August 1997   29th April 1998   29th February 2000   Half-n-half Clue   7.   guitar   trumpet   violin   harp   Half-n-half Clue