| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficulty of [verb] such | 14 |
|
| 2 | difficulty of [v-ing] such | 14 |
|
| 3 | difficulty of [verb] such | 14 |
|
| 4 | difficulties of [verb] such | 7 |
|
| 5 | difficulty of [verb] such | 7 |
|
