How many times does the biwords "que gregorio" appear in the language?
que gregorio refers to w1st = wid where word = 'que' AND w2nd = wid where word = 'gregorio'; appear refers to biwords.occurrences
SELECT occurrences FROM biwords WHERE w1st = ( SELECT wid FROM words WHERE word = 'que' ) AND w2nd = ( SELECT wid FROM words WHERE word = 'gregorio' )