| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be essential for [noun pl] [to-vb] | 5 |
|
| 2 | be essential [prep] [noun pl] [to-vb] | 5 |
|
| 3 | is essential [prep] [noun pl] [to-vb] | 5 |
|
| 4 | be essential [prep] [noun pl] [to-vb] | 5 |
|
| 5 | be essential for [noun pl] [to-vb] | 5 |
|
