| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [pers pn] [modal v] have been necessary [prep] | 6 |
|
| 2 | [pers pn] [vb mod] have been necessary [prep] | 6 |
|
| 3 | [pers pn] have been necessary [prep] [noun] | 5 |
|
