| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is difficult [to-vb] [adj] [noun] | 62 |
|
| 2 | is difficult [verb] [adj] [noun pl] | 34 |
|
| 3 | is difficult [verb] [adj] [noun sg] | 26 |
|
| 4 | is difficult to find [adj] [noun] | 7 |
|
| 5 | is difficult find [adj] [noun] | 7 |
|
| 6 | is difficult obtain [adj] [noun] | 6 |
|
| 7 | is difficult to obtain [adj] [noun] | 6 |
|
| 8 | is difficult [verb] precise [noun] | 5 |
|
