user: Question: What was the highest average point rating for a Modern suspense show with 21 episodes?
Columns: ['Airing date', 'English title (Chinese title)', 'Number of episodes', 'HD format', 'Highest average point ratings', 'Genre', 'Official website']
Types: ['text', 'text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['24 Dec 2007- 18 Jan 2008', "Survivor's Law II 律政新人王II", 20.0, 'No', 31.0, 'Modern drama', 'Official website']
SQL:

assistant: SELECT MAX("Highest average point ratings") FROM "Table" WHERE "Genre" = 'Modern suspense' AND "Number of episodes" = 21.0;