| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] when it [is] | 183 |
|
| 2 | [verb] when it [is] | 181 |
|
| 3 | [verb] when it is | 131 |
|
| 4 | [vb pp] when it [is] | 80 |
|
| 5 | [verb] when it 's | 52 |
|
| 6 | [vb -s] when it [is] | 31 |
|
| 7 | [vb infin] when it [is] | 26 |
|
| 8 | [to-vb] when it [is] | 20 |
|
| 9 | [vb base] when it [is] | 12 |
|
| 10 | [v-ing] when it [is] | 10 |
|
| 11 | happen when it [is] | 10 |
|
| 12 | do when it [is] | 9 |
|
| 13 | happens when it [is] | 7 |
|
