| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is [adv] difficult [verb] | 558 |
|
| 2 | because it is [adv] [verb] | 72 |
|
| 3 | because it is difficult [verb] | 17 |
|
| 4 | because it is [adv] difficult | 16 |
|
