| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [to-vb] at [adv] [adj] | 410 |
|
| 2 | required [to-vb] [adv] [adj] | 52 |
|
| 3 | required [to-vb] at [adv] | 10 |
|
| 4 | required [to-vb] at [adj] | 9 |
|
