| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | if it [vb past] [been] necessary | 5 |
|
| 2 | if it [vb past] [be] necessary | 5 |
|
| 3 | if it [vb past] be necessary | 5 |
|
| 4 | if it [vb past] been necessary | 5 |
|
