user: Question: On which date did episode # 18 air in the U.S.?
Columns: ['No.', '#', 'Title', 'Directed by', 'Written by', 'U.S. air date', 'Production code', 'U.S. viewers (million)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [196.0, 1.0, '"Lazarus"', 'Kevin G. Fair', 'Don Whitehead & Holly Henderson', 'September24,2010', '3X6001', '2.98']
SQL:

assistant: SELECT "U.S. air date" FROM "Table" WHERE "#" = 18.0;