| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be necessary | 1964 |
|
| 2 | it is necessary | 1407 |
|
| 3 | it was necessary | 425 |
|
| 4 | it 's necessary | 95 |
|
| 5 | it be necessary | 23 |
|
| 6 | it were necessary | 6 |
|
