| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is often [adj] [to-vb] the | 49 |
|
| 2 | is often difficult [to-vb] the | 13 |
|
| 3 | is often possible [to-vb] the | 9 |
|
| 4 | is often necessary [to-vb] the | 5 |
|
