| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb pp] [prep] be necessary | 54 |
|
| 2 | [vb pp] to [be] necessary | 54 |
|
| 3 | shown [prep] [be] necessary | 9 |
|
| 4 | thought [prep] [be] necessary | 8 |
|
| 5 | found [prep] [be] necessary | 5 |
|
