"The opera is not over before the big woman sings."
Translation:Dorbe' ghe'naQ bompa' be' tIn.
I'm on the van side of the discussion. I don't think it's simply a question of whether the it might sort of have a natural end, but rather whether someone can end it. An opera can be ended at any time and so its end, whether the natural end or an abrupt interruption is still described by van. A time period, however, can not, in general concept, be ended early. That time period must continue until it reaches its end, which is then described by Dor.