Which tense describes an action completed before another past action, as in 'had already left'?

• A. Past Simple
• B. Past Perfect
• C. Present Perfect
• D. Future Perfect

Answer: (B)

This tests how we show that one action in the past happened before another past action. The past perfect tense does exactly that: it describes an action that was completed before another action in the past. It is formed with had plus the past participle, as in had left. In a sentence like "When I arrived, she had already left," the leaving is the earlier action, and the arriving is the later one. The word already emphasizes that the first action was finished before the second occurred. Other tenses don’t express that same relative timing: present perfect connects to the present, future perfect looks to the future, and past simple only places actions in the past without marking which happened first in relation to another past event. So the tense used to indicate an action completed before another past action is past perfect.