| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [adv] difficult [to-vb] [coord] | 136 |
|
| 2 | [adv] difficult [verb] [coord] | 136 |
|
| 3 | [adv] difficult to obtain [conj] | 6 |
|
| 4 | [adv] [adj] to obtain [coord] | 6 |
|
| 5 | [adv] difficult to obtain [coord] | 5 |
|
| 6 | [adv] difficult obtain [coord] | 5 |
|
