| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficulty [prep] [verb] these [noun] | 13 |
|
| 2 | difficulty [prep] [v-ing] these [noun] | 13 |
|
| 3 | difficulty [prep] [verb] these [noun pl] | 13 |
|
| 4 | difficulty [prep] [verb] these [noun] | 13 |
|
| 5 | difficulty [prep] [verb] these [noun] | 9 |
|
| 6 | difficulty in [verb] these [noun] | 9 |
|
| 7 | difficulty in [verb] these [noun] | 9 |
|
