| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | happen be [vb pp] | 15 |
|
| 2 | happen are [verb] | 8 |
|
| 3 | happen was [verb] | 8 |
|
| 4 | happen is [verb] | 8 |
|
| 5 | happen be [verb] | 8 |
|
| 6 | happen be [v-ing] | 7 |
|
