| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must be [vb pp] [prep] [art] | 2033 |
|
| 2 | be [vb pp] [prep] [be] [art] | 230 |
|
| 3 | must be [vb pp] [prep] [be] | 75 |
|
| 4 | must be [vb pp] [be] [art] | 13 |
|
