| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | they must [verb] | 1582 |
|
| 2 | they must [vb infin] | 1579 |
|
| 3 | [pron] must know | 388 |
|
| 4 | [pers pn] must know | 368 |
|
| 5 | they [modal v] know | 259 |
|
| 6 | they must know | 35 |
|
| 7 | they must know | 34 |
|
