Q: "Three people smile as they wait for their race to start." Does this mean that "They are waiting at the starting line."?
A: yes

Q: "A man working with wood while sitting on the ground." Does this mean that "The man is standing up hammering a nail."?
A: no

Q: "Large black and white dog jumping in the snow." Does this mean that "a dog jumps"?
A: yes

Q: "Two people sitting on a cement bench chatting over lunch." Does this mean that "Two men sitting on a cement bench chatting over lunch."?
A:
it is not possible to tell