| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be [adv] essential for | 30 |
|
| 2 | it be [adv] essential for | 30 |
|
| 3 | it is [adv] essential for | 24 |
|
| 4 | it be [adv] essential for | 20 |
|
| 5 | it be not essential for | 10 |
|
| 6 | it be not essential for | 10 |
|
| 7 | it be [not/n't] essential for | 10 |
|
