| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | to understand [Wh det] is [v-ing] on | 14 |
|
| 2 | to understand [pron] is going on | 14 |
|
| 3 | to understand what is [v-ing] on | 14 |
|
| 4 | to understand what is [v-ing] on | 14 |
|
