| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb base] back to the [adj] century | 12 |
|
| 2 | [vb base] back [prep] the [adj] century | 12 |
|
| 3 | [vb base] back [prep] the [num ord] century | 12 |
|
| 4 | [vb base] back to the [adj] century | 12 |
|
| 5 | go back [prep] the [adj] century | 6 |
|
| 6 | date back [prep] the [adj] century | 6 |
|
