| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | but it [is] [adv] difficult [verb] | 46 |
|
| 2 | but it [is] [adv] difficult [verb] | 40 |
|
| 3 | [conj] it [is] often difficult [verb] | 23 |
|
| 4 | but it [is] often [adj] [verb] | 8 |
|
| 5 | but it [is] often [adj] [verb] | 6 |
|
| 6 | but [pron] [is] often difficult [verb] | 5 |
|
| 7 | but it [be] often difficult [verb] | 5 |
|
| 8 | but it [is] often difficult [verb] | 5 |
|
| 9 | but it [is] often difficult [verb] | 5 |
|
