user: Question: What was the cause of death in the marriage that lasted 28 years? 
Columns: ['Name', 'Deceased Spouse', 'Cause of Death', 'Date of Spouses Death', 'Length of Marriage', 'Children Together', 'Current Marital Status']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Samuel Beckett', 'Suzanne Déchevaux-Dumesnil', 'Unknown', 'July 17, 1989 (aged89)', '28 years', 'None', 'Deceased (1989)']
SQL:

assistant: SELECT "Cause of Death" FROM "Table" WHERE "Length of Marriage" = '28 years';