| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] back [prep] the last [noun sg] | 19 |
|
| 2 | [verb] back to the last [noun sg] | 9 |
|
| 3 | [verb] back to the last [noun sg] | 9 |
|
| 4 | [v-ing] back [prep] the last [noun sg] | 8 |
|
| 5 | date back [prep] the last [noun sg] | 5 |
|
| 6 | [verb] back [prep] the last century | 5 |
|
