| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is [to-vb] [adj] | 2410 |
|
| 2 | is necessary [to-vb] | 1319 |
|
| 3 | necessary [to-vb] [adj] | 763 |
|
| 4 | is necessary [adj] | 31 |
|
