user: Question: Which Airing date has a Number of episodes larger than 20, and a Genre of Modern drama?
Columns: ['Airing date', 'English title (Chinese title)', 'Number of episodes', 'Theme song (T) Sub-theme song (ST)', 'Genre']
Types: ['text', 'text', 'real', 'text', 'text']
Sample row: ['9 January– 3 Feb', 'The Romance of the White Hair Maiden 白髮魔女傳', 20.0, 'T: "等你到白頭" ( Mo Kai Yin & Cass Phang )', 'Costume drama']
SQL:

assistant: SELECT "Airing date" FROM "Table" WHERE "Number of episodes" > 20.0 AND "Genre" = 'Modern drama';