user: Question: What is the Termination of Mission date for Marsha E. Barnes, the Ambassador Extraordinary and Plenipotentiary?
Columns: ['Representative', 'Title', 'Presentation of Credentials', 'Termination of Mission', 'Appointed by']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Robert L. Flanagin', "Chargé d'Affaires ad interim", 'Nov 25, 1975', 'Mar 25, 1976', 'Gerald Ford']
SQL:

assistant: SELECT "Termination of Mission" FROM "Table" WHERE "Title" = 'Ambassador Extraordinary and Plenipotentiary' AND "Representative" = 'Marsha E. Barnes';