| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | shown to be [adj] | 235 |
|
| 2 | shown to be [adj] | 227 |
|
| 3 | [verb] to be essential | 31 |
|
| 4 | [vb pp] to be essential | 13 |
|
| 5 | show to be essential | 5 |
|
| 6 | shown to be essential | 5 |
|
| 7 | shown to [be] essential | 5 |
|
| 8 | shown to [be] essential | 5 |
|
| 9 | shown to be essential | 5 |
|
| 10 | shown [prep] be essential | 5 |
|
