| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [v-ing] [prep] [art] | 2556 |
|
| 2 | must be [prep] [art] | 382 |
|
| 3 | must be [v-ing] [prep] | 161 |
|
| 4 | must be [v-ing] [art] | 59 |
|
