ผู้ชมคนใดมีภาษาของ troff (typesetter runoff) groff (gnu runoff)?ไม่จำเป็นที่จะต้องใช้ตารางทั้งหมด
Which viewers have the language of troff (typesetter runoff)  groff (gnu runoff)?It is not neccessary to use all the tables.
 table_1574968_1:  (viewer [ VARCHAR ] language [ VARCHAR) ]
SELECT viewer FROM table_1574968_1 WHERE language = "troff (typesetter runoff) , groff (GNU runoff)"