| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is [adj] | 38935 |
|
| 2 | it [be] necessary | 1964 |
|
| 3 | it be necessary | 1964 |
|
| 4 | [pron] is necessary | 1533 |
|
| 5 | it [is] necessary | 1502 |
|
