Please list the title of the pages on which the word "grec" occurred for over 20 times.
occurred for over 20 times refers to occurrences > 20;
SELECT T3.title FROM words AS T1 INNER JOIN pages_words AS T2 ON T1.wid = T2.wid INNER JOIN pages AS T3 ON T2.pid = T3.pid WHERE T1.word = 'grec' AND T2.occurrences > 20