| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | back [prep] the 18th [noun sg] | 9 |
|
| 2 | back [prep] the 18th century | 8 |
|
| 3 | back to the 18th [noun sg] | 6 |
|
| 4 | back to the 18th [noun sg] | 6 |
|
