CREATE TABLE table_28138035_6 (womens_doubles VARCHAR(255), womens_singles VARCHAR(255), mens_singles VARCHAR(255))
How many times did  li ju win the womens singles and wang liqin win the mens singles?
    
SQL: SELECT COUNT(womens_doubles) FROM table_28138035_6 WHERE womens_singles = "Li Ju" AND mens_singles = "Wang Liqin"