| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [be] [v-ing] | 10696 |
|
| 2 | [prep] [be] [v-ing] | 7764 |
|
| 3 | [prep] it [be] | 4434 |
|
| 4 | [prep] it [v-ing] | 458 |
|
