
Verbo regular: happen - happened - happened
Forma simple | Forma con V-ing | 
| - - it ought to happen - - -  | - - it ought to be happening - - -  | 
Perfecto | Perfecto con V-ing | 
| - - it ought to have happened - - -  | - - it ought to have been happening - - -  | 
Forma simple | Forma con V-ing | 
| - - it oughtn't to happen - - -  | - - it oughtn't to be happening - - -  | 
Perfecto | Perfecto con V-ing | 
| - - it oughtn't to have happened - - -  | - - it oughtn't to have been happening - - -  | 
Forma simple | Forma con V-ing | 
| - - ought to it happen? - - -  | - - ought to it be happening? - - -  | 
Perfecto | Perfecto con V-ing | 
| - - ought to it have happened? - - -  | - - ought to it have been happening? - - -  | 
Forma simple | Forma con V-ing | 
| - - oughtn't it to happen? - - -  | - - oughtn't it to be happening? - - -  | 
Perfecto | Perfecto con V-ing | 
| - - oughtn't it to have happened? - - -  | - - oughtn't it to have been happening? - - -  |