| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is [adv] [to-vb] | 3033 |
|
| 2 | is necessary [to-vb] | 1319 |
|
| 3 | is [adv] necessary | 1024 |
|
| 4 | [adv] necessary [to-vb] | 766 |
|
