| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is [verb] | 200716 |
|
| 2 | is [vb pp] | 136581 |
|
| 3 | be required | 6747 |
|
| 4 | [be] required | 6747 |
|
| 5 | [is] required | 2562 |
|
| 6 | is require | 2561 |
|
