| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | if they had been [v-ing] | 22 |
|
| 2 | if they have been [v-ing] | 8 |
|
| 3 | if they 'd been [v-ing] | 7 |
|
| 4 | if they 've been [v-ing] | 6 |
|
