12.1* complete the sentence with the past simple or past perfect simple form of the verb in brackets: 1. when i (try) tried to use my laptop, i realized the battery (run) down. 2. i (turn) the computer off, but forgot that i (not save) my work. 3. i only remembered i (not pay) the bill when my internet connection (stop) working. 4. when i (receive) the e-mail, i couldn't understand who (send) it. 5. when i (check) the instructions, i understood what i (do) 6. i knew i (receive) a virus when i (run) the anti-virus program. 7. as soon as i (download) the document, i knew i (make) a mistake. 8. i could see what (go) wrong as soon as i (look) inside the printer. 9. i knew i (press) the wrong key when nothing (happen) 10. when the screen (go) blank, i couldn't understand how it (happen)
