| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is [adj] | 38935 |
|
| 2 | it [be] difficult | 2948 |
|
| 3 | it be difficult | 2948 |
|
| 4 | it [is] difficult | 2398 |
|
| 5 | [pron] is difficult | 1968 |
|
