turn when a sentence is not finished.
* Gap: A period of silence between turns, for example after a question has been asked and not yet answered
* Lapse: A period of silence when no sequence or other structured activity is in progress: the current speaker stops talking, does not select a next speaker, and no one self selects. Lapses are commonly associated with visual or other forms of disengagement between speakers, even if these periods are brief.

Some types of turns may require extra work before they can successfully take