| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is [adj] [conj] it [verb] | 395 |
|
| 2 | is useful [conj] [pron] [verb] | 18 |
|
| 3 | [be] useful [conj] it [verb] | 17 |
|
| 4 | be useful [conj] it [verb] | 17 |
|
| 5 | [is] useful [conj] it [verb] | 11 |
|
