CREATE TABLE table_28138035_20 (mens_doubles VARCHAR2, womens_singles VARCHAR2)

How many people are shown for mens doubles when guo yue played womens singles?
SELECT COUNT(mens_doubles) FROM table_28138035_20 WHERE womens_singles = "Guo Yue"
SELECT COUNT("mens_doubles") FROM "table_28138035_20" WHERE "Guo Yue" = "womens_singles"