[Q] Given the sentence "A person in an apron is selling many different sized fish on a stand." is it true that "A person  is selling fish."?
[A] Selling many different sized fish is a sufficient condition for selling fish.
The answer is yes.

[Q] Premise: "A little girl in a pink and yellow plaid dress is crying with her arms crossed in front of her."
Hypothesis: "The girl is crying because she was told she couldn't have candy."
Do we know that the hypothesis entailed by the premise?
[A] A girl crying is not assumed to be doing so because she was told she couldn't have candy.
The answer is it is not possible to tell.

[Q] Premise: "Several people are riding a roller coaster."
Hypothesis: "Two of whom are blond women with small children beside them."
Do we know that the hypothesis entailed by the premise?
[A] Two blond woman with small children wait the turn for a roller coaster ride.
The answer is no.