| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] 1990 when the [noun sg] | 6 |
|
| 2 | [prep] 1990 when the [noun sg] | 6 |
|
| 3 | in 1990 when the [noun sg] | 6 |
|
| 4 | [prep] 1990 when the [noun sg] | 6 |
|
