| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | must [vb infin] [verb] at | 64 |
|
| 2 | must [verb] [verb] at | 64 |
|
| 3 | must have [verb] at | 57 |
|
| 4 | must [verb] [vb pp] at | 57 |
|
| 5 | must have [verb] at | 57 |
|
| 6 | must [verb] look at | 7 |
|
| 7 | must [verb] looked at | 7 |
|
