| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [v-ing] [prep] a | 27354 |
|
| 2 | [was/were] [v-ing] [prep] | 26019 |
|
| 3 | [was/were] [prep] a | 5287 |
|
| 4 | [was/were] [v-ing] a | 4665 |
|
