user: Question: Who won the men's doubles before 1979 when Carol Silman Prina Ben Shushan won the women's doubles?
Columns: ['Year', "Men's singles", "Women's singles", "Men's doubles", "Women's doubles", 'Mixed doubles']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1977.0, 'Victor Yusim', 'Chaya Grunstein', 'Victor Yusim Michael Schneidman', 'Vivian Meirowitz Carol Silman', 'Michael Schneidman Dianne Levi']
SQL:

assistant: SELECT "Men's doubles" FROM "Table" WHERE "Year" < 1979.0 AND "Women's doubles" = 'Carol Silman Prina Ben Shushan';