| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is necessary [verb] certain [noun] | 5 |
|
| 2 | [pron] is necessary [verb] certain [noun] | 5 |
|
| 3 | [pers pn] is necessary [verb] certain [noun] | 5 |
|
| 4 | it is necessary [verb] certain [noun] | 5 |
|
