Maîtrise des temps du passé : Past Simple, Continuous, Perfect

Complétez le paragraphe suivant en conjuguant les verbes entre parenthèses au temps approprié (Past Simple, Past Continuous ou Past Perfect) :

'Last night, while I (study) for my English exam, the power (go) out. I (not / finish) my assignment yet, so I was quite stressed. My brother, who (read) a book in the living room, (come) to help me with a flashlight. By the time he arrived, I (realize) that I (save) my document online already.'