List down the email address of female single employees.
female refers to Gender = 'F'; single refers to MaritalStatus = 'S';
SELECT T3.EmailAddress FROM Employee AS T1 INNER JOIN Person AS T2 ON T1.BusinessEntityID = T2.BusinessEntityID INNER JOIN EmailAddress AS T3 ON T2.BusinessEntityID = T3.BusinessEntityID WHERE T1.Gender = 'F' AND T1.MaritalStatus = 'S'