| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [is] [subord] [prep] | 388 |
|
| 2 | [is] difficult [prep] | 344 |
|
| 3 | difficult [subord] [prep] | 70 |
|
| 4 | [is] difficult [subord] | 64 |
|
