CREATE TABLE table_77093 ("Date" TEXT, "Round" TEXT, "Opponent" TEXT, "Venue" TEXT, "Result" TEXT, "Attendance" FLOAT)

Who played against in venue a on 17 february 1900?
SELECT "Opponent" FROM table_77093 WHERE "Venue" = 'a' AND "Date" = '17 february 1900'
SELECT "Opponent" FROM "table_77093" WHERE "Date" = '17 february 1900' AND "Venue" = 'a'