| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which [vb base] back to the | 10 |
|
| 2 | which [vb base] back to the | 10 |
|
| 3 | which [vb base] back [prep] the | 10 |
|
| 4 | which [vb base] back [prep] the | 10 |
|
| 5 | which date back [prep] the | 8 |
|
