| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | who have been [verb] for a | 21 |
|
| 2 | who have been [v-ing] for a | 17 |
|
| 3 | who had been [verb] for a | 8 |
|
| 4 | who have been [verb] for a | 6 |
|
