| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it [is] often refer [prep] | 7 |
|
| 2 | it [is] often refer to | 7 |
|
| 3 | it [is] often refer [prep] | 7 |
|
| 4 | it [is] often refer to | 7 |
|
