| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb past] it [verb] [noun] | 195 |
|
| 2 | [vb past] it necessary [verb] | 118 |
|
| 3 | it necessary [verb] [noun] | 45 |
|
| 4 | [vb past] necessary [verb] [noun] | 6 |
|
