| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [be] difficult to see | 235 |
|
| 2 | it be difficult to see | 235 |
|
| 3 | it [is] difficult to see | 203 |
|
| 4 | it is difficult to see | 185 |
|
| 5 | it [was/were] difficult to see | 32 |
|
| 6 | it was difficult to see | 32 |
|
| 7 | it 's difficult to see | 18 |
|
