Write SQL query to solve given problem: What's the occurrence of the biwords pair whose first word is "àbac" and second word is "xinès"?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT occurrences FROM biwords WHERE w1st = ( SELECT wid FROM words WHERE word = 'àbac' ) AND w2nd = ( SELECT wid FROM words WHERE word = 'xinès' )