| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | at an [noun] | 1398 |
|
| 2 | at an [noun sg] | 1270 |
|
| 3 | at [art] airport | 232 |
|
| 4 | at [art] airport | 232 |
|
| 5 | [prep] an airport | 39 |
|
| 6 | at an airport | 7 |
|
| 7 | at a airport | 7 |
|
