| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be often [vb pp] [to-vb] | 12 |
|
| 2 | it is often [verb] [to-vb] | 11 |
|
| 3 | it be often used [to-vb] | 7 |
|
| 4 | it be often use [to-vb] | 7 |
|
