| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] [adv] once in a | 11 |
|
| 2 | [adv] [subord] once in a | 6 |
|
| 3 | [adv] than once in a | 6 |
|
| 4 | [adv] [conj] once in a | 6 |
|
| 5 | [adv] than once in a | 6 |
|
| 6 | [adv] once in a [noun] | 20 |
|
| 7 | [adv] once in a [noun sg] | 20 |
|
| 8 | [adv] once in a while | 10 |
|
| 9 | [adv] once in a while | 10 |
|
| 10 | [adv] once in a [adj] | 7 |
|
| 11 | [adv] once in a lifetime | 6 |
|
| 12 | [adv] once in a lifetime | 6 |
|
| 13 | [adv] once in a [adj] | 5 |
|
