(1) He keeps trying to get it published but I think he's flogging a dead horse.

(2) Pam's flogging a dead horse trying to organize the theatre trip. It's quite obvious that nobody's interested.

(3) They seem to be flogging a dead horse.

(4) If something is carried on then it is flogging a dead horse or blind ambition.

(5) Glitter is Dot Cotton in foot-thick panstick, flogging a dead horse until its bones are a pile of dust.

(6) Don't try to flog a dead horse.

(7) It is useless to flog a dead horse.

(8) Son, we 've been over this so many times. The answer is "no". Don't flog a dead horse!