| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have been several attempts | 8 |
|
| 2 | [vb base] been several attempts | 8 |
|
| 3 | [verb] been several attempts | 8 |
|
| 4 | have been several attempts | 7 |
|
| 5 | been several attempts [to-vb] | 6 |
|
| 6 | been several attempts [verb] | 6 |
|
