user: Question: What is the average Mean, when Drug is "alcohol", and when Psychological Dependence is greater than 1.9?
Columns: ['Drug', 'Mean', 'Pleasure', 'Psychological dependence', 'Physical dependence']
Types: ['text', 'real', 'real', 'real', 'real']
Sample row: ['Heroin', 3.0, 3.0, 3.0, 3.0]
SQL:

assistant: SELECT AVG("Mean") FROM "Table" WHERE "Drug" = 'alcohol' AND "Psychological dependence" > 1.9;