| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | back in [adj] | 682 |
|
| 2 | back in [num] | 421 |
|
| 3 | [adv] in 1990 | 123 |
|
| 4 | [adv prt] in 1990 | 45 |
|
| 5 | back [prep] 1990 | 16 |
|
| 6 | back [prep] 1990 | 16 |
|
| 7 | back in 1990 | 14 |
|
| 8 | back in 1990 | 14 |
|
| 9 | back in 1990 | 14 |
|
