| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | which [be] required for | 18 |
|
| 2 | which be required for | 18 |
|
| 3 | which [is] required for | 9 |
|
| 4 | which is required for | 9 |
|
| 5 | which [am/are] required for | 7 |
|
| 6 | which are required for | 7 |
|
