| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | when [verb] back [prep] | 15 |
|
| 2 | when [verb] back [prep] | 15 |
|
| 3 | when [vb pp] back [prep] | 8 |
|
| 4 | when [v-ing] back [prep] | 7 |
|
| 5 | when [verb] back to | 6 |
|
