| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have never [adv] exist | 10 |
|
| 2 | [verb] never [adv] existed | 10 |
|
| 3 | [vb past] never [adv] exist | 6 |
|
| 4 | had never [adv] exist | 6 |
|
