| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficulty [prep] [verb] to the [adj] | 7 |
|
| 2 | difficulty [prep] [v-ing] to the [adj] | 7 |
|
| 3 | difficulty [prep] [verb] to the [adj] | 7 |
|
| 4 | difficulty in [verb] to the [adj] | 6 |
|
| 5 | difficulty in [verb] to the [adj] | 6 |
|
| 6 | difficulty [prep] [verb] to the [adj] | 6 |
|
