| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] be [v-ing] | 7764 |
|
| 2 | be [v-ing] when | 373 |
|
| 3 | [prep] [v-ing] when | 179 |
|
| 4 | [prep] be when | 47 |
|
