| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | take place [prep] a background of | 22 |
|
| 2 | take place against a background of | 22 |
|
| 3 | take place [prep] a background of | 22 |
|
| 4 | took place [prep] a background of | 14 |
|
