| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [is] [adv] useful for [verb] [art] | 5 |
|
| 2 | [is] [adv] useful for [v-ing] [art] | 5 |
|
| 3 | is [adv] useful for [verb] [art] | 5 |
|
