| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [modal v] be back [prep] | 527 |
|
| 2 | be trace back [prep] | 124 |
|
| 3 | [modal v] be trace [prep] | 123 |
|
| 4 | [modal v] be trace back | 110 |
|
