QUESTION: Given the sentence "The young man with the colorful flowered lei and colorful bracelets is holding a flag." is it true that "A young man holding a japanese flag."?

Let's solve it slowly: The young man with the colorful flowered lei and colorful bracelets is holding a flag does not mean that he holding a Japanese flag.
The answer is it is not possible to tell.

QUESTION: Premise: "A child watches a man shape a ceramic object on a potter's wheel."
Hypothesis: "A ceramic object is being molded."
Do we know that the hypothesis entailed by the premise?

Let's solve it slowly: A ceramic object is molded or shaped using a potter's wheel.
The answer is yes.

QUESTION: Premise: "A man in black approaches a strange silver object containing a person."
Hypothesis: "While many onlookers observe from behind a roped off barrier."
Do we know that the hypothesis entailed by the premise?

Let's solve it slowly:
The strange silver object is a UFO and the person inside has been abducted by aliens.
The answer is no.