| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [modal v] [be] [v-ing] to | 603 |
|
| 2 | [be] [v-ing] back to | 388 |
|
| 3 | [modal v] [be] [v-ing] back | 133 |
|
| 4 | [modal v] [be] back to | 58 |
|
