| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] to be essential | 31 |
|
| 2 | [vb pp] [prep] be essential | 13 |
|
| 3 | seem [prep] be essential | 7 |
|
| 4 | [vb past] [prep] be essential | 6 |
|
| 5 | show [prep] be essential | 5 |
|
| 6 | shown [prep] be essential | 5 |
|
