user: Question: When was the win/Lose Lose and the round a Play-off?
Columns: ['Edition', 'Round', 'Date', 'Against', 'Surface', 'Opponent', 'Win/Lose', 'Result']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['2010 Europe/Africa Zone Group I', 'QF', '7–8 May 2010', 'Ukraine', 'Clay', 'Sergiy Stakhovsky', 'Lose', '2–6, 7–6 (7–3) , 5–7, 5–7']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Win/Lose" = 'Lose' AND "Round" = 'Play-off';