Change the following from active to passive: The laboratory will have double-checked the reagents by dawn.

Question

Change the following from active to passive:

The laboratory will have double-checked the reagents by dawn.

1. A. The reagents have been double-checked by the laboratory by dawn.
2. B. The reagents will have been double-checked by the laboratory by dawn. (Correct answer)
3. C. The reagents will be double-checked by the laboratory by dawn.
4. D. The reagents would have been double-checking by the laboratory by dawn.

Correct Answer

Option B — The reagents will have been double-checked by the laboratory by dawn.

Detailed Solution & Explanation

The correct answer is The reagents will have been double-checked by the laboratory by dawn.

Key Points

• The active sentence is in the future perfect — *will have double-checked* — so the passive must be the future perfect passive.
• Its structure is will have been + past participle.
• The object *the reagents* becomes the subject, the agent *the laboratory* follows by, and the time phrase *by dawn* is retained.
• The distractors shift tense: option A is present perfect, C is simple future, and D is a conditional perfect.

Additional Information

• Passive forms by tense: simple present *is done*, present continuous *is being done*, present perfect *has been done*, simple past *was done*, past continuous *was being done*, past perfect *had been done*, simple future *will be done*, **future perfect *will have been done***.
• The perfect continuous tenses have no natural passive, which is why they never appear in these options.
• Converting voice must never change the tense — only the arrangement of subject, verb and object moves.