
Regular verb: happen - happened - happened
| Present | Present continuous | Preterite | Preterite continuous | 
| - - does it not happen? - - - | - - is it not happening? - - - | - - did it not happen? - - - | - - was it not happening? - - - | 
| Present perfect | Present perfect continuous | Pluperfect | Pluperfect continuous | 
| - - has it not happened? - - - | - - has it not been happening? - - - | - - had it not happened? - - - | - - had it not been happening? - - - | 
| Future | Future continuous | Future perfect | Future perfect continuous | 
| - - will it not happen? - - - | - - will it not be happening? - - - | - - will it not have happened? - - - | - - will it not have been happening? - - - | 
| Present | Present continuous | Past | Past continuous | 
| - - would it not happen? - - - | - - would it not be happening? - - - | - - would it not have happened? - - - | - - would it not have been happening? - - - | 
| Infinitive | Imperative | 
| Infinitive | Imperative | ||
| to happen | - - - | 
| Present | Past | ||
| happening | happened |