| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | to be useful [prep] a | 8 |
|
| 2 | to be useful [prep] a | 8 |
|
| 3 | to [be] useful [prep] a | 8 |
|
| 4 | to [be] useful [prep] a | 8 |
|
| 5 | to [be] useful [prep] a | 6 |
|
