Final answer:
The sentence, 'I wrote the exam well yesterday,' is already in the active voice because it presents the subject (I) as performing the action (writing the exam). Active voice provides clear, direct, and concise sentences.
Step-by-step explanation:
In English grammar, sentences can be written in two 'voices': active and passive. When you transform a sentence from passive voice to active voice, the subject of the sentence becomes the doer of the action rather than the recipient. To change your sentence 'The exam was written well by me yesterday' (passive) into active voice, it would be 'I wrote the exam well yesterday'.
Active-voice verbs create stronger, clearer, and more concise sentences, indicating a direct action. Your sentence already demonstrates this well, displaying the subject (I) performing the action (wrote the exam).
Learn more about Active and Passive Voice