| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is useful for [v-ing] [art] | 11 |
|
| 2 | is useful for [verb] [art] | 11 |
|
| 3 | is useful for [verb] [art] | 11 |
|
| 4 | is useful for [verb] the | 9 |
|
| 5 | is useful for [verb] the | 9 |
|
