| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be necessary for the purpose [prep] | 5 |
|
| 2 | [be] necessary for the purpose [prep] | 5 |
|
| 3 | necessary for the purpose [prep] [verb] | 7 |
|
| 4 | necessary for the purpose [prep] [v-ing] | 7 |
|
