| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is difficult [to-vb] [art] | 334 |
|
| 2 | is difficult [to-vb] such | 14 |
|
| 3 | difficult [to-vb] such [art] | 14 |
|
| 4 | is [to-vb] such [art] | 13 |
|
