| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which is [adv] difficult [verb] | 19 |
|
| 2 | which [is] [adv] difficult [to-vb] | 19 |
|
| 3 | which [is] [adv] difficult [verb] | 19 |
|
| 4 | which [is] very difficult [verb] | 5 |
|
