Nothing had _________________ done by them.
Nothing had _________________ done by them.
Explanation
The past perfect tense requires "had" plus the past participle of the verb.
The past participle of "be" is "been".
Nothing had been done by them.
The past perfect tense requires "had" plus the past participle of the verb.
The past participle of "be" is "been".
Nothing had been done by them.