| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is [adj] | 38935 |
|
| 2 | it be essential | 1036 |
|
| 3 | it [be] essential | 1036 |
|
| 4 | [pron] is essential | 911 |
|
| 5 | it [is] essential | 899 |
|
