user: Question: What's the mountains classification of Stage 7 when Kim Kirchen was the general classification?
Columns: ['Stage', 'Winner', 'General Classification', 'Mountains Classification', 'Points Classification', 'Sprints classification', 'Team Classification']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1', 'Óscar Freire', 'Óscar Freire', 'no award', 'Óscar Freire', 'no award', "Caisse d'Epargne"]
SQL:

assistant: SELECT "Mountains Classification" FROM "Table" WHERE "General Classification" = 'Kim Kirchen' AND "Stage" = '7';