Complete the sentences with the correct past forms of the verb in brackets.
16. Tom (read) a book while I (clean) my room. 20. Owen (write) a letter when the light (go) out.
17. David (invite) Carol to the party yesterday but she (already/plan) the day. 21. Jason (work) in the garden for hours before he (take) a break.
18. What (you listen) to when I (come) in? 22. Three days ago Liza (return) me the book I (lend) her before.
19. Tina (watch) TV for three hours before the phone (ring). 23. Mary (arrange) everything by the time we (arrive).

16) was reading, was cleaning

17) invited, had already planned

18) were you listening, came

19) had been watching, rang

20) was writing, went

21) had been working, took

22) returned, had lent

23) had arranged, arrived