| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be [v-ing] [prep] a | 6866 |
|
| 2 | [vb mod] be [v-ing] [prep] | 4042 |
|
| 3 | [vb mod] be [prep] a | 1134 |
|
| 4 | [vb mod] be [v-ing] a | 819 |
|
