Final answer:
To convert 'A dark cloud was seen by me' into active voice, it becomes 'I saw a dark cloud.'
Step-by-step explanation:
In English grammar, voice refers to the form of a verb that indicates whether the subject of a sentence performs or receives the action. In this case, the dark cloud is the subject and it is being transformed from a passive voice to an active voice. In passive voice, the subject receives the action, while in active voice, the subject performs the action. To change the dark cloud from passive voice to active voice, you would rephrase the sentence to make the cloud the subject and the person or thing doing the action would become the object.
The sentence in active voice would be 'I saw a dark cloud.'