| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | it is [adj] refer [prep] | 26 |
|
| 2 | it is [adj] to refer [prep] | 26 |
|
| 3 | it is [adj] refer to | 25 |
|
| 4 | it is necessary refer [prep] | 8 |
|
