| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [prep] serving as [art] | 15 |
|
| 2 | [prep] serve as [art] | 15 |
|
| 3 | [prep] serve as a | 14 |
|
| 4 | [prep] serve as a | 11 |
|
| 5 | after serve as [art] | 6 |
|
