Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Outcome | Year | Championship | Surface | Partner | Opponents | Score |
| --- | --- | --- | --- | --- | --- | --- |
| Runner-up | 1969.0 | US Open | Grass | Margaret Court | Françoise Dürr Darlene Hard | 0–6, 6–4, 6–4 |
| Runner-up | 1970.0 | Wimbledon | Grass | Françoise Dürr | Rosie Casals Billie Jean King | 6–2, 6–3 |
| Runner-up | 1970.0 | US Open | Grass | Rosie Casals | Margaret Court Judy Tegart Dalton | 6–3, 6–4 |
| Runner-up | 1972.0 | US Open | Grass | Margaret Court | Françoise Dürr Betty Stöve | 6–3, 1–6, 6–3 |
| Winner | 1973.0 | Australian Open | Grass | Margaret Court | Kerry Harris Kerry Melville | 6–4, 6–4 |
| Winner | 1973.0 | French Open | Clay | Margaret Court | Françoise Dürr Betty Stöve | 6–2, 6–3 |
| Winner | 1973.0 | US Open | Grass | Margaret Court | Rosie Casals Billie Jean King | 2–6, 6–3, 7–5 |
| Winner | 1975.0 | US Open | Clay | Margaret Court | Rosie Casals Billie Jean King | 7–5, 2–6, 7–6(5) |
| Runner-up | 1976.0 | US Open | Clay | Olga Morozova | Linky Boshoff Ilana Kloss | 6–1, 6–4 |
Question:
On what surface was the game played with a score of  6–4, 6–4?
Answer:
Grass