| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [was/were] [verb] on [num] december [adj] | 28 |
|
| 2 | [was/were] [verb] on [num] [noun] 1991 | 22 |
|
| 3 | [be] [verb] on [num] december 1991 | 7 |
|
| 4 | [was/were] [verb] on [adj] december 1991 | 5 |
|
| 5 | [was/were] [verb] [prep] [num] december 1991 | 5 |
|
