| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [is] [adj] [to-vb] | 27518 |
|
| 2 | [is] [adj] [to-vb] | 25675 |
|
| 3 | [be] difficult [to-vb] | 3945 |
|
| 4 | [is] difficult [verb] | 2249 |
|
| 5 | [is] difficult [to-vb] | 2237 |
|
