| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun prp] had been [v-ing] on | 29 |
|
| 2 | [noun sg] had been [v-ing] on | 23 |
|
| 3 | [noun] had been working on | 17 |
|
| 4 | [noun pl] had been [v-ing] on | 12 |
|
