| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is difficult [to-vb] exactly | 9 |
|
| 2 | is difficult [to-vb] just | 9 |
|
| 3 | is difficult [to-vb] precisely | 8 |
|
| 4 | is difficult [to-vb] accurately | 8 |
|
| 5 | is difficult to say [adv] | 7 |
|
