| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | had [be] [verb] at | 699 |
|
| 2 | had [be] working [prep] | 156 |
|
| 3 | had [be] working [prep] | 156 |
|
| 4 | had [be] [v-ing] at | 148 |
|
| 5 | have [be] working at | 41 |
|
| 6 | [verb] [be] working at | 41 |
|
| 7 | [vb past] [be] working at | 20 |
|
| 8 | had [be] work at | 19 |
|
| 9 | had [be] working at | 18 |
|
