the firemen succeeded in putting the fire out after five hours
the pop star was invited to the chat show, but he didn't turn up 

20. Firefighters extinguished the fire after five hours.
→ Firefighters successfully put out the fire after 5 hours
21. We invited a pop star on a talk show, but he didn't come. (turn)
→ Pop stars don't come when we invite them on the show

20. The firemen succeeded in putting it out after five hours.
21. The pop star that we invited onto the chat show didn’t turn up.