| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | difficult [to-vb] how | 314 |
|
| 2 | difficult to see [Wh adv] | 200 |
|
| 3 | difficult [to-vb] why | 94 |
|
| 4 | difficult to understand [Wh adv] | 56 |
|
| 5 | difficult to know [Wh adv] | 52 |
|
| 6 | difficult [to-vb] where | 43 |
|
| 7 | difficult to explain [Wh adv] | 21 |
|
| 8 | difficult to imagine [Wh adv] | 20 |
|
| 9 | difficult to say [Wh adv] | 20 |
|
| 10 | difficult [to-vb] when | 18 |
|
| 11 | difficult to tell [Wh adv] | 13 |
|
| 12 | difficult to decide [Wh adv] | 12 |
|
| 13 | difficult to judge [Wh adv] | 10 |
|
| 14 | difficult to predict [Wh adv] | 7 |
|
| 15 | difficult to determine [Wh adv] | 6 |
|
| 16 | difficult to envisage [Wh adv] | 5 |
|
