| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | had been [verb] on a | 108 |
|
| 2 | have been working on a | 26 |
|
| 3 | [verb] been working on a | 26 |
|
| 4 | had been working [prep] a | 24 |
|
| 5 | had been working [prep] a | 24 |
|
| 6 | had been working on [art] | 21 |
|
| 7 | had been [v-ing] on a | 16 |
|
| 8 | [vb past] been working on a | 8 |
|
| 9 | had been work on a | 8 |
|
| 10 | had be working on a | 7 |
|
| 11 | had [been] working on a | 7 |
|
| 12 | had [be] working on a | 7 |
|
| 13 | had been working on a | 7 |
|
