| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun] [prep] [det] | 259987 |
|
| 2 | [noun pl] [prep] [det] | 66769 |
|
| 3 | difficulty [prep] [det] | 283 |
|
| 4 | difficulties [prep] [adj] | 280 |
|
