| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it be not unknown for | 54 |
|
| 2 | it [be] not unknown for | 54 |
|
| 3 | it [be] not unknown for | 54 |
|
| 4 | it [be] not unknown for | 53 |
|
| 5 | it [is] not unknown for | 38 |
|
| 6 | it is not unknown for | 35 |
|
| 7 | it [was/were] not unknown for | 16 |
|
| 8 | it was not unknown for | 16 |
|
