| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | is often [vb pp] [verb] [adj] | 15 |
|
| 2 | is often [vb pp] [to-vb] [adj] | 15 |
|
| 3 | is often [vb pp] [verb] [adj] | 13 |
|
| 4 | is often used [verb] [adj] | 10 |
|
