Change the following sentence into the Active form.
The experiment had been completed by the scientists.
Show answer & explanation
Correct answer: C
Explanation
The original sentence, "The experiment had been completed by the scientists," is in the passive voice and uses the past perfect tense (had been completed). To change it to the active voice, the subject (the scientists) must perform the action (completed) directly, while maintaining the same tense. The active voice past perfect tense structure is "had + past participle". Therefore, "The scientists had completed the experiment" is the correct active form.