| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | prevent them [prep] [v-ing] | 170 |
|
| 2 | not prevent them [prep] | 11 |
|
| 3 | not prevent [prep] [v-ing] | 10 |
|
| 4 | not prevent them [v-ing] | 5 |
|
