user: Question: Name the capacity for Single cab size 2 Medium tanker
Columns: ['Category', 'Sub-category', 'Cab size', 'Drive wheels', 'Capacity (litres)']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['1 Heavy tanker', 'Village', 'Crew', '4x4', '3,000 - 4,000']
SQL:

assistant: SELECT "Capacity (litres)" FROM "Table" WHERE "Cab size" = 'Single' AND "Category" = '2 Medium tanker';