Fill in the blank by choosing he correct form of the Verb. By the time I met him, he __________ reading the voluminous novel.

EXPLANATION: The sentence describes an action in the past before another past event (meeting him). "By the time" indicates a completed action before the meeting occurred. "Had finished" is the past perfect tense, which is used to express an action completed before another past action. "Was finishing" is the past continuous tense, which indicates an ongoing action in the past, not a completed one. "Will finish" is the future tense, not relevant to the past actions described. "Finished" alone is the simple past tense, not specific enough to indicate the completion before the meeting.