| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | have been [vb pp] to be [adj] | 67 |
|
| 2 | [vb base] been shown to be [adj] | 30 |
|
| 3 | [vb base] been found to be [adj] | 15 |
|
| 4 | [vb base] been [vb pp] to be effective | 7 |
|
