| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [is] [adv] useful [prep] [verb] | 52 |
|
| 2 | which [is] [adv] useful [prep] | 14 |
|
| 3 | which [is] [adv] [prep] [verb] | 12 |
|
| 4 | which [is] useful [prep] [verb] | 6 |
|
