Question: How many combination classifications have the winner as Erik Zabel and a points classification as Alessandro Petacchi
SQL: SELECT COUNT("Combination classification") FROM "1-15059783-1" WHERE "Points classification" = 'Alessandro Petacchi' AND "Winner" = 'Erik Zabel';

Question: If winner is Alejandro Valverde and the points Classification is by Erik Zabel, who is the mountain classification?
SQL: SELECT "Mountains classification" FROM "1-15059783-1" WHERE "Winner" = 'Alejandro Valverde' AND "Points classification" = 'Erik Zabel';

Question: How many teams have a combination classification of Alejandro Valverde and a Points classification of Alessandro Petacchi?
SQL: SELECT COUNT("Team classification") FROM "1-15059783-1" WHERE "Combination classification" = 'Alejandro Valverde' AND "Points classification" = 'Alessandro Petacchi';