Select the most appropriate form of the past tense that can substitute the highlighted segment to rectify the given sentence.
By the time I reached the station, the train already left.

Correct option is A

The correct substitution of the highlighted words is (a) had already left.
Explanation: The sentence refers to two past actions, where one (train leaving) occurred before the other (reaching the station). Therefore, the Past Perfect Tense (had + past participle) is used for the earlier action.
Corrected sentence: By the time I reached the station, the train had already left.
Grammatical rule used:
When two past actions occur, the action that happens first is expressed in Past Perfect Tense, and the later action in Simple Past Tense.
Example: When I arrived, he had gone to bed.
Information Booster:
“Already” is often used with Perfect Tenses to indicate that something happened sooner than expected.