CREATE TABLE table_name_24 (time VARCHAR(255), news_freq VARCHAR(255), local_networked VARCHAR(255), ad_freq VARCHAR(255))
Which time has a local/networked value of Local, ad frequency of every 20 minutes, and news frequency of n/a after 7PM news?
    
SQL: SELECT time FROM table_name_24 WHERE local_networked = "local" AND ad_freq = "20 minutes" AND news_freq = "n/a after 7pm news"