| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] a [noun] [prep] | 149076 |
|
| 2 | back [prep] [noun] [prep] | 1644 |
|
| 3 | back [prep] a [noun] | 921 |
|
| 4 | back a [noun] [prep] | 137 |
|
