Question: Which opponent was on July 21, 2008?
SQL: SELECT "Opponent" FROM "2-18504248-6" WHERE "Date" = 'July 21, 2008';

Question: What was the date of the tournament with a Clay surface and an opponent of Irina Falconi?
SQL: SELECT "Date" FROM "2-18504248-6" WHERE "Surface" = 'Clay' AND "Opponent" = 'Irina Falconi';

Question: Who was the opponent on May 10, 2009?
SQL: SELECT "Opponent" FROM "2-18504248-6" WHERE "Date" = 'May 10, 2009';