| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [be] useful [prep] [be] [adj] | 10 |
|
| 2 | it [be] useful [prep] [be] able | 10 |
|
| 3 | it [be] useful to [be] [adj] | 10 |
|
| 4 | it [be] useful [prep] be [adj] | 10 |
|
| 5 | it [is] useful [prep] [be] [adj] | 10 |
|
| 6 | it be useful [prep] [be] [adj] | 10 |
|
| 7 | it is useful [prep] [be] [adj] | 7 |
|
