| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | had been [v-ing] on [prep] the | 10 |
|
| 2 | had [been] [v-ing] on [prep] the | 10 |
|
| 3 | had be [v-ing] on [prep] the | 10 |
|
| 4 | had [be] going on [prep] the | 6 |
|
