| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [vb past] be [prep] | 348 |
|
| 2 | it be necessary [prep] | 270 |
|
| 3 | it [vb past] be necessary | 13 |
|
| 4 | [vb past] be necessary [prep] | 9 |
|
| 5 | it [vb past] necessary [prep] | 7 |
|
