1) [ hadn’t been ][ wouldn’t have missed ]
2) [ had studied ][ would have passed ]
3) [ had arrived ][ would have seen ]
4) [ had gone ][ wouldn’t have woken ]
5) [ had become ][ would have recorded ]
6) [ had gone ][ would have become ]
7) [ had been ][ would have learned ]
8) [ had gone ][ would have studied ]
9) [ hadn’t gone ][ wouldn’t have met ]
10) [ hadn’t taken ][ would have gone ]
11) [ would have been ][ had stayed ]
12) [ would have passed ][ had studied ]
13) [ wouldn’t have got ][ hadn’t gone ]
14) [ would have been ][ hadn’t taken ]
15) [ wouldn’t have met ][ hadn’t come ]
16) [ would have taken ][ had had ]
17) [ would have called ][ hadn’t forgotten ]
18) [ would have come ][ had been ]
19) [ wouldn’t have done ][ had known ]
20) [ would have been ][ had left ]