
Regular verb: happen - happened - happened
| Present | Present continuous | Preterite | Preterite continuous | 
| - - it happens - - - | - - it's happening - - - | - - it happened - - - | - - it was happening - - - | 
| Present perfect | Present perfect continuous | Pluperfect | Pluperfect continuous | 
| - - it's happened - - - | - - it's been happening - - - | - - it'd happened - - - | - - it'd been happening - - - | 
| Future | Future continuous | Future perfect | Future perfect continuous | 
| - - it'll happen - - - | - - it'll be happening - - - | - - it'll have happened - - - | - - it'll have been happening - - - | 
| Present | Present continuous | Past | Past continuous | 
| - - it'd happen - - - | - - it'd be happening - - - | - - it'd have happened - - - | - - it'd have been happening - - - | 
| Infinitive | Imperative | 
| Infinitive | Imperative | ||
| to happen | - Let's happen - | 
| Present | Past | ||
| happening | happened |