| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | be used for [adj] years | 17 |
|
| 2 | been used for [adj] years | 15 |
|
| 3 | [been] used for [adj] years | 15 |
|
| 4 | [be] used for [det] years | 14 |
|
| 5 | [be] used for many years | 12 |
|
| 6 | [be] used for many years | 12 |
|
