Change the following from active to passive:
The professor could have been explaining differential topology for hours.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. Differential topology could have been being explained for hours by the professor.
About the given sentence:
Type of sentence: Assertive
Tense: Perfect Continuous (with Modal "could")
Given voice: Active voice
Subject: The professor
Object: Differential topology
Structure for conversion:
Active: Subject + modal + have + been + verb (ing form) + object...
Passive: Object + modal + have + been + being + verb (IIIrd form) + by + subject...
Converted sentence: Differential topology could have been being explained for hours by the professor.
Hence, the chosen option is correct.