| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [v-ing] [noun] [prep] an | 641 |
|
| 2 | when [v-ing] [noun] [prep] | 317 |
|
| 3 | when [v-ing] [prep] an | 29 |
|
| 4 | when [noun] [prep] an | 7 |
|
