| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | but it [is] [adv] difficult | 56 |
|
| 2 | but it [is] [adv] difficult | 56 |
|
| 3 | but it is [adv] difficult | 35 |
|
| 4 | but it [is] very difficult | 28 |
|
| 5 | but it 's [adv] difficult | 21 |
|
| 6 | but it [is] often difficult | 5 |
|
