| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [vb infin] be [noun sg] | 52 |
|
| 2 | must have be [noun sg] | 48 |
|
| 3 | must have be [noun sg] | 47 |
|
| 4 | must [verb] been [noun sg] | 47 |
|
