| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must be [vb pp] [prep] | 4919 |
|
| 2 | also be [vb pp] [prep] | 1982 |
|
| 3 | must also be [vb pp] | 299 |
|
| 4 | must also be [prep] | 13 |
|
