| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [conj] [pers pn] is often necessary [verb] | 6 |
|
| 2 | [conj] it is often necessary [verb] | 6 |
|
| 3 | [conj] [pron] is often necessary [verb] | 6 |
|
| 4 | [conj] it is often necessary [verb] | 6 |
|
| 5 | [conj] [pron] is often necessary [to-vb] | 5 |
|
