Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_21001903_2 (tour VARCHAR, mixed_doubles VARCHAR, womens_singles VARCHAR)
### Question:
when mixed doubles is zheng bo ma jin and womens singles is wang yihan, what was the tour?
### Answer:
SELECT tour FROM table_21001903_2 WHERE mixed_doubles = "Zheng Bo Ma Jin" AND womens_singles = "Wang Yihan"