premise: Five girls and two guys are crossing a overpass. hypothesis: There are people outside.
entailment: The fact that these are people is implied by "girls" and "guys".  An "overpass" is used only in context of being outside, referring to a road crossing over another road.  Roads are almost always outside, particularly for this type of interchange.|entailment: Five girls and two guys are people, and overpass implies outside.|entailment: An overpass is found outdoors.