Answer:
"He didn't jump into the water"
"Did he jump into the water?"
Explanation:
To rewrite the positive "He jumped into the water" sentence to negative and interrogative the following grammar rules must be taken into account:
Negative: an article must be prepended denying the verb, which, being a sentence in the past tense, will be conjugated with the verb did.
"He didn't jump into the water"
Interrogative: the verb did must be placed before the person.
"Did he jump into the water?"
