| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have been building up [prep] the | 10 |
|
| 2 | [verb] been building up [prep] the | 10 |
|
| 3 | had been building up [prep] the | 7 |
|
| 4 | [vb past] been building up [prep] the | 7 |
|
