Just when I thought I had it...So, for Q3, when do we truly know when to ignore 'without' as an indicator? Is it when there is a sufficient indicator at the beginning?

What's with "Never" being an indicator when that wasn't stated?

Loved the way he explained this. Subset (NYC) membership is sufficient (Okay) for superset (USA) membership because you have to be in the USA to be NYC but it is not necessary because you can be the Grand Canyon and still be in the USA.

While

Superset (USA) membership is necessary (needed) for subset (NYC) membership because you have to be in the USA but not sufficient if its earth.