| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [v-ing] [prep] a | 27354 |
|
| 2 | [prep] a period | 2137 |
|
| 3 | [v-ing] a period | 75 |
|
| 4 | [v-ing] [prep] period | 15 |
|
