| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is required to be | 39 |
|
| 2 | are required to be | 34 |
|
| 3 | be required to be | 26 |
|
| 4 | were required to be | 17 |
|
| 5 | was required to be | 13 |
|
