Answer and Explanation:
The sentences provided are basically in two types of mood: indicative and imperative. The indicative serves to express a state or something that is happening at the moment. The imperative is used for commands and requests. The interrogative mood, the one we are asked to rewrite the sentences in, is basically asking a question.
Question: 2. Ben (scratched) his nose as he (stood) by the fence. - indicative (both verbs)
Did Ben scratch his nose as he stood by the fence?
Question: 3. (Let) me whitewash a little! - imperative
Will you let me whitewash a little?
Question: 4. (Give) Ben the brush, and then (watch) him work. - imperative (both verbs)
Will you give Ben the brush, and then watch him work?
Question: 5. After a while, Tom (was rolling) in wealth. - indicative
Was Tom rolling in wealth after a while?
Question: 6. (Trade) the tadpoles for a chance to whitewash the fence. - imperative
Will you trade the tadpoles for a chance to whitewash the fence?