| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [to-vb] [prep] [art] [noun] | 44241 |
|
| 2 | difficult [to-vb] [art] [noun] | 852 |
|
| 3 | difficult [to-vb] [prep] [art] | 443 |
|
| 4 | difficult [prep] [art] [noun] | 423 |
|
| 5 | difficult [to-vb] [prep] [noun] | 309 |
|
