| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is [to-vb] [adj] [noun pl] | 369 |
|
| 2 | difficult [to-vb] [adj] [noun pl] | 140 |
|
| 3 | is difficult [to-vb] [adj] | 77 |
|
| 4 | is difficult [to-vb] [noun pl] | 44 |
|
