Fill in the blanks with the simple past or past perfect form of the verbs given in brackets. (i) After Rohan A. _____ (finish) his homework, he B. _____ (decide) to go for a walk. He C. _____ (leave) the house and D. _____ (realise) he E. _____ (forget) his keys inside. (ii) By the time we A. _____ (reach) the station, the train B. _____ (already/leave). We C. _____ (wait) for the next one to arrive.
(i) A. had finished, B. decided, C. left, D. realised, E. had forgotten (ii) A. reached, B. had already left, C. waited
Explanation
Past perfect is used when one past action happened before another past action. In (i), finishing homework happened before deciding, and forgetting keys happened before realising. In (ii), the train leaving happened before reaching the station, so 'had already left' is used. The waiting happened after reaching, so simple past 'waited' is appropriate.