Premise: "A man in a white shirt doing some kind of work on a street."
Hypothesis: "A man is working on the street."
Do we know that the hypothesis entailed by the premise?

yes
Explanation: Doing work on a street implies that he is working on the street..

Given the sentence "Man in yellow shirt performing maintenance on schwinn bicycle near a picnic table." is it true that "The man is changing the tire on his bicycle."?

it is not possible to tell
Explanation: Changing a bike tire is not the only type of maintenance one can do..

Premise: "The dog walks on the high plank."
Hypothesis: "A dog walks across a plank."
Do we know that the hypothesis entailed by the premise?

yes
Explanation: Answer: The dog walks on the plank. The fact that it is high is not relevant..

Premise: "A shirtless man and another in a gray shirt are looking at large blue and yellow corrugated tubes going down into a blue rimmed hole."
Hypothesis: "The men looked at the tubes trying to figure out where the leak was."
Do we know that the hypothesis entailed by the premise?
it is not possible to tell
Explanation: You cannot know that there is a leak in the tubes they are just giving a description of the tubes..