| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] to be necessary [prep] | 20 |
|
| 2 | [vb pp] to [be] necessary [prep] | 20 |
|
| 3 | [vb pp] to be necessary [prep] | 20 |
|
| 4 | [vb pp] to [be] necessary for | 14 |
|
| 5 | shown to [be] necessary [prep] | 5 |
|
