| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [noun sg] must be [prep] | 327 |
|
| 2 | must be [v-ing] [prep] | 161 |
|
| 3 | [noun sg] must be [v-ing] | 119 |
|
| 4 | [noun sg] be [v-ing] [prep] | 37 |
|
