Question

The time for the current iteration is up and one of the features isn't complete. What do you do?

Answer 1

Answer:

Stop working and add the incomplete feature back into the backlog.

Explanation:

In case a task could not be completed in the current iteration, it is best to add it to the backlog, so that in subsequent iterations it will be completed (giving it priority, of course).  

Of course, it is not convenient to extend the iteration time just to finish the incomplete task. Also, we should not add it directly to the next iteration because we would be altering its structure. So the most appropriate thing to do, is to leave it marked as a priority to be included in the next iterations.