| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [vb -s] been [vb pp] in some study | 6 |
|
| 2 | [vb -s] be [vb pp] in some studies | 6 |
|
| 3 | [vb -s] be [vb pp] in some study | 6 |
|
| 4 | has be [vb pp] in some study | 6 |
|
