Q: "A dog leaping into the water near a motorboat." Does this mean that "A dog leaping into the water near a boat."?
A: yes

Q: "A family walking with three pieces of luggage." Does this mean that "Nobody is walking"?
A: no

Q: "Two nicely dressed young men standing next to a street signal pole." Does this mean that "Two men are standing waiting for their friend to meet them."?
A: it is not possible to tell

Q: "Two uniformed police officers are holding large guns, while an older man sits on the stairs, holding his hat and looking on." Does this mean that "There are officers on duty."?
A:
yes