| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [was/were] become [adv] difficult | 8 |
|
| 2 | it [was/were] become [adv] difficult | 8 |
|
| 3 | it [was/were] become increasingly difficult | 6 |
|
| 4 | it [was/were] become increasingly difficult | 6 |
|
| 5 | it [was/were] become difficult [verb] | 5 |
|
| 6 | it [was/were] become difficult [to-vb] | 5 |
|
