13. woke up, looked, was, had been snowing
14. looked, had passed
15. admitted, had made, apologized
16. sent, had made, had been attending
17. ran, had used
18. got, heard, had cancelled
19. saw, was doing, was
20. had been working, dropped

13 woke up, looked, was, had been snowing
14 looked, had passed
15  admitted, had made, apologized
16 sent, had made,had been attented
17 ran, had used
18 got, heard, had cancelled
19 saw, had done, was
20 had been working, dropped
21 ran, was